Microstructure, Magnetism and Electrical Transport Properties of Mn-Ni-Sn based Heusler Alloy Thin Films Grown Using RF Magnetron Sputtering: Consequences of Annealing Conditions

Microstructure, Magnetism and Electrical Transport Properties of Mn-Ni-Sn based Heusler Alloy Thin Films Grown Using RF Magnetron Sputtering: Consequences of Annealing Conditions | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Microstructure, Magnetism and Electrical Transport Properties of Mn-Ni-Sn based Heusler Alloy Thin Films Grown Using RF Magnetron Sputtering: Consequences of Annealing Conditions Annu Verma, Komal Bhatt, Jai Dev Tanwar, Pallavi Kushwaha, Jai Shankar Tawale, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4540219/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The study investigates the effects of annealing on the structural, morphological, magnetic, and transport properties of Mn-Ni-Sn-based Heusler alloy thin films grown by UHV RF Magnetron sputtering. A commercial target with the nominal composition Mn 2 Ni 1.6 Sn 0.4 was used, and the films were deposited on (001) oriented SrTiO 3 substrates. Thin films were deposited at 500 °C, 600 °C, 700 °C, and 800 °C and in situ annealing was done at the respective deposition temperatures for 6 hours. X-ray reflectivity indicated a deposition rate of »4 nm/min. The films exhibited B2 or L2 1 -type structures, or a mixture of both, depending on the annealing temperature. At the highest growth temperature (800 °C), additional diffraction maxima between 40-45° were likely due to Ni 3 Sn or Mn 3 Sn impurity phases, suggesting thermally activated decomposition. Surface microstructures consisting of dark and bright regions evolved from continuous to discontinuous morphology with the increase of the growth temperature. The bifurcation between zero field-cooled (ZFC) and field-cooled warming (FCW) curves decreased, and the magnetic moment increased with deposition temperatures up to 700 °C. The Curie temperature for all films was above room temperature. Films grown at 500 °C, 600 °C, and 700 °C followed the Bloch law below 143 K. However, the film grown at 800 °C, followed this law between 14 K and 75 K. Films grown up to 700 °C behaved like a local magnetic moment system, which is crucial for spin polarization in Heusler systems. Phase degeneration at 800 °C destroyed the half-metallic behavior. All films showed metallic behavior with different resistivity and temperature dependence. Residual Resistivity Ratio (RRR) values were 1.17, 1.51, and 1.64 for films grown at 500 °C, 600 °C, and 700 °C, respectively. The phase degenerated film showed the steepest decline in resistivity, with an exceptionally high RRR of approximately 956.59. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Heusler alloys are a unique class of materials that can possess ferromagnetism with Curie temperature distributed over a wide temperature range of 200 K to 1200 K despite having all non-magnetic constituents [ 1 ]. In 1903, Fritz Heusler, while working on a compound composed of Cu, Mn, and Al, having the chemical composition Cu 2 MnAl, found out that it is ferromagnetic, although none of the constituents was magnetic by itself [ 2 ]. Since then, thousands of member alloys have been added to the Heusler family. The different aspects of Heusler systems have been reviewed over the years [ 1 , 3 – 9 ]. Structural strangeness is one of the major sources of the unique and diversified properties of these alloys. If X and Y are transition elements and Z is a main group element, the ratio XYZ = 1:1:1 is classified as the half Heusler variant, while the ratio XYZ = 2:1:1 represents the full Heusler family. The X 2 YZ crystallizes into the cubic L2 1 structure formed by four interpenetrating fcc sublattices; the atomic sites (tetrahedral sites) of the two sublattices are filled equally by the X element and the atomic sites of the other two (octahedral sites) are occupied by the Y and Z elements. The ordering of the different elements occupying different atomic positions is the key to the magnetic and electronic properties of these materials. The presence of disorder may cause structural transformations, e.g., the interstitial disordering of Y and Z sites yields the B2 cubic structural phase. Magnetism originates from the complex hybridization of the orbitals of the different constituents. The hybridization of \({d}_{{z}^{2}}\) and \({d}_{{x}^{2}-{y}^{2}}\) yields a low-energy bonding \({e}_{g}\) orbital and a high-energy antibonding \({e}_{u}\) orbital. The hybridization of \({d}_{xy}\) , \({d}_{yz}\) and \({d}_{zx}\) form a triply degenerate low-energy bonding \({t}_{2g}\) orbital and a triply degenerate high-energy antibonding \({t}_{1u}\) orbital [ 10 , 11 ]. Disorders in any form like chemical non-stoichiometry, interstitial disordering, changes in structure and atomic position swaps, modify the hybridization and hence the band structure. The effect of disorder on the half-metallic behavior is stronger than the structural changes as the minority spin band gap is sensitive to the local changes in hybridization. The magneto-electronic properties of Heusler materials are also impacted by heterointerfacing as it also changes the local hybridization in the proximity of the interfaces [ 12 , 13 ]. Ni-Mn-based full Heusler alloys, e.g., Ni 2 MnSn, Ni 2 MnGa, Ni 2 MnIn, Mn 2 NiSn, and their various substitutional variants have attained a special standing because of the occurrence of (i) austenite-martensite (AP-MP) transitions, (ii) intrinsic exchange bias, (iii) magnetocaloric effect, (iv) spin glass behavior and (v) magnetic anisotropy [ 14 – 25 ]. One of the interesting aspects of these alloys is the existence of mixed antiferromagnetic (AFM) and ferromagnetic (FM) interactions, and the interplay between them determines the magnetoelectrical phase profile. A T C of T C ~319 K with a cubic L2 1 structure and a magneto-structural (MS) phase transition at T AM =221 K during the cooling cycle and T MA =239 K in the warming cycle was reported by Brown and coworkers in Ni 2 Mn 1.44 Sn 0.56 [ 26 ]. The MS transitions are very sensitive to subtle changes in the chemical compositions and post-annealing. The importance of the Heusler alloys was demonstrated by the recent observation of the shell-ferromagnetic effect in Mn-rich AFM Heusler systems Ni 50 Mn 45 Z 5 (Z: Al, Ga, In, Sn, Sb) [ 27 ]. This effect occurs when the L2 1 -FM alloy with composition Ni 50 Mn 25 Z 25 and AFM-L1 0 Ni 50 Mn 50 coexist on annealing in the temperature range ~ 350–500 °C. The MS transitions, spin glass behavior, and the re-entrant ferromagnetism in the martensite state have also been demonstrated in the inverse Heusler alloy Mn 2 Ni 1.6 Sn 0.4 and its Cr-doped versions [ 27 , 28 , 29 ]. Small variations in the Mn/Ni ratio shift the T AM and T C to higher temperatures, cause hysteresis in resistivity and magnetization, and transform the low-temperature cluster glass into spin glass [ 29 ]. Thus, the inverse Heusler variants also offer an interesting area of investigation. The studies on Heusler alloy films are scarce, and those on Ni-Mn-Sn-containing compounds are very few. The studies on Heusler thin films are constrained by issues related to the control of the chemical constitution. Since thin films are important for electronic and spintronic applications in contemporary technology, the development of synthesis and annealing protocols that lead to the precise control of chemical composition and, hence, optimum and stable magnetic properties are warranted. Lund et al. [ 30 ] used MBE to grow epitaxial films of Ni 2 MnGa, Ni 2 MnGe, and Ni 2 MnAl on (001) oriented GaAs, with the first two alloys had the Curie temperature of T C ~340 K and ~ 300 K, respectively. The ρ-T of the FM of Ni 2 MnGa and Ni 2 MnGe alloys showed a peak and maximum negative MR near T C . A crossover from metallic to semiconducting behavior and the low-temperature resistivity upturn marks the unconventional metallic nature of these alloys. Co-Mn-based alloys, e.g., Co 2 MnSi, Co 2 MnSn, Co 2 MnAl, and Co 2 FeAl have been investigated by several groups over the past two decades [ 31 – 36 ]. Single-phase thin films of Co-Mn-based half-metallic Heusler compounds, namely Co 2 MnSi, Co 2 MnGe, and Co 2 MnSn (i) with the ordered L2 1 structure, (ii) very smooth surface morphology and (iii) pronounced (110) texture was deposited by RF magnetron sputtering on sapphire a-plane and (100)-MgO [ 32 ]. Fe-site Cr substituted Co 2 FeAl Heusler alloy film having a B2 structure on thermally oxidized Si had a magnetic moment of 2.04 µ B /fu, suggesting a localized nature of ferromagnetism, which is a necessary condition for half metallicity [ 33 ]. Cu 2 MnAl and Co 2 MnSi films grown at low temperatures (~ 150–200 °C), are paramagnetic (PM) and had higher resistivity (~ 100–200 µΩ-cm), while those grown at higher temperatures had lower resistivity and were FM, with T C ~600 °C and ~ 950 °C [ 35 ]. The temperature-dependent resistivity (ρ-T) followed a \(\rho \left(T\right)\simT\) dependence in the range 300 K-100 K, while at T<100 K, it followed \(\rho \left(T\right)\sim{T}^{2}+{T}^{\raisebox{1ex}{$9$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}\) . Here, the first term denotes either the one-magnon (1m) scattering or the electron-electron (e-e) scattering, and the second term accounts for the two-magnon (2m) scattering [ 36 ]. J. Dubowik et al. [ 37 ] magnetron sputtered Ni 50 Mn 35 Sn 15 (Ni 2 Mn 1.4 Sn 0.6 ) thin films on (001)-MgO substrates at 350 °C at 2 mTorr of Ar pressure and annealed them at 800 °C to achieve structural ordering. These films are chemically ordered with (00l) oriented with lattice constant a=0.598 nm but magnetically inhomogeneous with the AFM order extending into the austenite phase. About 30% lower magnetic moment in the MP than that in AP was attributed to the decrease in the Mn-Mn distance. Vishnoi and Kaur performed several studies on about 1 µm thick Ni 50 Mn 50−x Sn x (x=15,16, 18, 22) films on Si substrate [ 38 , 39 ]. Ni 52.6 Mn 23.7 Sn 23.6 and Ni 51.5 Mn 26.1 Sn 22.2 films showed an austenite phase with a mixed L2 1 /A2+B2 structure. On the other hand, Ni 58.9 Mn 28.0 Sn 13.0 and Ni 58.3 Mn 29.0 Sn 12.6 films show a martensitic phase with a 14M modulated monoclinic structure. Substitution of Sn by Mn causes structural instability that, in turn, impacts the magnetic properties of these films [ 39 ]. Vishnoi and Kaur [ 39 ] have also reported the exchange bias effect in the martensitic state of Ni 49.8 Mn 36.1 Sn 13.9 film. They attributed it to the unidirectional anisotropy that arises due to the coupling between AFM and FM interactions in the martensite phase of the film. Barsha Borgohain et al. [ 40 ] have investigated 400 nm thick Ni 51 Mn 33 Cr 5 Sn 11 films deposited on (001)-MgO by dc magnetron sputtering and reported (i) enhanced T C ~321 K, (ii) the occurrence of austenite-martensite transitions over a very broad range, (iii) exchange bias effect in lower temperature region. The above survey shows that very little work has been done on the Ni-Mn-X-based alloys. These alloy systems still lack an optimized growth and annealing protocol required to grow thin films that achieve desired properties reproducibly. In the current study, the effect of annealing up to a temperature of 800 ℃ on structural features, surface morphology, chemical composition, magnetic, and transport properties in off-stoichiometric Mn-Ni-Sn based Heusler alloy thin films. We have found that annealing at very high temperatures has a profound effect on the properties of the thin films. Experimental Details Mn 2 Ni 1.6 Sn 0.4 thin films were grown using an ultra-high vacuum (UHV) RF magnetron sputtering on (001)-oriented SrTiO 3 (STO) substrates. A commercially procured alloy target with a nominal composition of Mn 2 Ni 1.6 Sn 0.4 and 2-inch in diameter was used for deposition. The target thickness was ~ 3 mm. The target-to-substrate distance was fixed at ~ 5 cm. The base pressure of the deposition chamber was 1.5×10 − 6 mTorr, and the depositions were carried out at the optimized Ar pressure of 2 mTorr. Before deposition, the substrates were cleaned thoroughly with boiled acetone then with isopropyl alcohol, and at last with deionized water. The substrate temperature (t S ) was varied from 500 °C to 800 °C in the steps of 100 °C. During deposition, the substrate was rotated at a speed of 10 rpm to ensure deposition uniformity, and the RF power was maintained at 50 W. Pre-deposition sputtering was done for about fifteen minutes to ensure the same state of target at all depositions and removal of any impurities that can be present. The RF sputtering was done for 10 minutes. All the films were annealed in situ for six hours at the respective deposition temperatures. The thickness of the films was estimated by X-ray reflectivity (XRR), and the average deposition rate was estimated to be ~ 3.6 nm/minute under the above-mentioned conditions. The structural characterization was done using a powder X-ray diffractometer with Cu K α radiation (Rigaku Ultima Ⅳ) and a high-resolution X-ray diffractometer employing Cu K α1 radiation (PANalytical, X′Pert PRO MRD). A Quantum design magnetic property measurements system (MPMS) (MPMS XL 7) was used for magnetization measurements at a magnetic field of H = 1000 Oe in the temperature range 5 K – 300 K. The transport measurements were done in the four-probe linear contact geometry with the temperature ranging from 4.2 K to 300 K. A field emission scanning electron microscope (FESEM) (Zeiss EVO MA 10, Oxford INCA 250) equipped with energy dispersive spectroscopy (EDS) was used to estimate the chemical composition and surface morphology. Results and Discussion For the present study, we have chosen the films deposited for 10 minutes and annealed at the respective deposition temperatures for 6 hours in Ar ambient. The estimation of the film thickness was done by XRR. The XRR of films deposited for different durations under the same experimental conditions was done, and the film thickness was estimated using the formula \(D=\frac{m\lambda }{2\sqrt{{\left(\text{sin}{\theta }_{i}\right)}^{2}- {\left(\text{sin}{\theta }_{c}\right)}^{2}}}\) where \({{\theta }}_{c}\) is the critical angle and \({{\theta }}_{\text{i}}\) is the angle corresponding to the m th order Kiessig fringe. The representative XRR pattern of a film with a 2-minute deposition time is shown in Fig. 1 . The thickness of the film was ~ 7.2 nm and this gives a deposition rate of ~ 3.6 nm per minute. Thus, the approximate thickness of the present films is ~ 40 nm. The structural characterization was done by high resolution and powder x-ray diffractometry (HR-XRD and P-XRD) using CuK α1 (1.5406 Å) and CuK α (1.5418 Å) radiations. The obtained powder and high-resolution XRD patterns are plotted in Fig. 2 . The P-XRD pattern of the film deposited and annealed at 500 °C (denoted by 5C) (Fig. 2 a) shows the occurrence of the (200) superlattice reflections and the principal (400) reflections. This indicates the formation of an ordered B2 phase. In addition, the (220) is also present in the XRD pattern, which suggests the presence of the fcc L2 1 -type structure as well as the existence of a long-range atomic order. The second-order super lattice peak (222) is also present, and it supports the long-range order with the fcc L2 1 structure. However, in the case of B2 type structure, which has a lesser degree of order than the L2 1 structure, the (222) may have a weaker presence than the (200) and (400) reflections or it may not appear at all. The HRXRD scan shows the occurrence of the (200) and (400) reflections. Thus, the film deposited and annealed at 500 °C has a mixture of the B2 and L2 1 phases. As the growth temperature is increased from 500 °C to 600 °C (film denoted by 6C), the (220) and (222) diffraction maxima vanish (Fig. 2 b), and only (200) and (400) peaks appear in P-XRD as well as the HRXRD. The disappearance of (220) and (222) peaks shows the presence of the B2 phase due to the reduced atomic order. The film grown at a further higher temperature of 700 °C also shows similar structural features; however, the occurrence of a small but sharp peak at 2θ = 41.76° indicates the presence of an impurity. A decomposition of the B2 Heusler structure is possible at higher growth temperatures. In Mn-Ni-Sn based Heusler systems the occurrence of impurity phases like Ni 3 Sn or Mn 3 Sn may take place due to non-stoichiometric growth conditions. The most plausible alloys in the present case seem to be Ni 3 Sn and Mn 3 Sn; both have dominant XRD peaks of around 2θ = 41.76°. In the case of cubic Ni 3 Sn and Mn 3 Sn, the (021) peak appears around Ni 3 Sn and Mn 3 Sn around 2θ = 41.76°. In the powder XRD pattern (Fig. 2 d) of the film deposited and annealed at 800 °C (8C), the (200) and (400) peaks are observed. In addition, several diffraction maxima, mostly located between 40–45°, are seen. As seen in Fig. 2 d, these peaks are sharper and distinct from the peaks that characterize the cubic Heusler L2 1 or B2 phases. A closer look at the P-XRD pattern of the film grown at 800 °C shows that the additional peaks appearing at 2θ = 34.2°, 39.46°, 41.8°, 42.62°, and 43.46° could belong to the Ni 3 Sn phase having a closest packed hexagonal structure (space group \(P{6}_{3}/mmc\) ) and lattice constants a = 5.296 Å and c = 4.248 Å [ 41 ]. The formation of the phase is driven by the evaporation of Mn due to the higher growth and annealing temperature of 800 °C. As discussed above the alloys Ni 3 Sn or Mn 3 Sn could appear as the impurity phases due to the thermally activated decomposition of the parent Heusler phase. The out-of-plane lattice constants of the films grown at 500 °C, 600 °C, 700 °C, and 800 °C are found to be 6.165 Å, 5.998 Å, 5.984 Å and 6.015 Å, respectively. The increase in the lattice constant of the film grown at 800 °C could be due to the chemical inhomogeneity and formation of secondary phases. The chemical composition of all four films was examined by EDS attached to FESEM. The EDS spectra were recorded from five places in each film and the average composition was determined. Representative FESEM pictures of all films at the same magnification are shown in Fig. 3 . It can be seen in the images that the surface microstructure consists of two phases: darker region and bright particles spread over the film surface. As seen in Fig. 3 a, the surface morphology of the films grown at 500 °C is mostly continuous, and small particles are distributed over the surface sporadically. The overall composition of the film is Mn 2.16 Ni 1.56 Sn 0.30 . The bright particles over the film surface seem to come out of the film due to thermal stresses due to the thermal expansion coefficient mismatch between the film and the substrate STO. An increase in the film growth temperature has a degenerative influence on the surface morphology. In the film grown at 600 ℃, the continuity of the darker regions is disrupted, and the brighter particles appear to increase in size as well as density. The average chemical composition of the majority darker region of this film is Mn 2.10 Ni 1.56 Sn 0.34 . The brighter particles are nearly equiatomic in Mn and Ni but very low in Sn content. Since the particles are distantly placed, the transport behavior is not expected to be affected much by them. However, their chemical composition may have an impact on the magnetic characteristics. The surface morphology of the film grown at 700 °C is shown in Fig. 3 c. Most of the surface still consists of the dark layer; however, the layer itself becomes more discontinuous. As a result, the bright particles become larger and higher in number density. The average composition of the darker layer is Mn 1.9 Ni 1.66 Sn 0.43 , while the brighter regions remain nearly equiatomic in Mn and Ni and low in Sn content. Thus, the film grown at 700 °C shows an Mn deficient Heusler phase but also has Ni 3 Sn and Mn 3 Sn as the impurity phases. Growth temperature higher than 700 °C leads to an enhancement in the number-density and size of the bright particles which, become dominant in the surface morphology. The average composition of these particles is Mn 0.21 Ni 2.98 Sn 0.81 suggesting the formation Ni 3 Sn majority and Mn 3 Sn minority phases. The dark regions look highly disrupted, and their average composition is Mn 0.91 Ni 2.76 Sn 0.33 . Thus, higher temperature growth, e.g., at 700 °C and 800 °C is not conducive to the stability of the Heusler phases. The temperature dependence of magnetization (M – T) was measured in the temperature range of 300 K– 5 K in the zero-field cooled (ZFC), field-cooled cooling (FCC), and field-cooled warming (FCW). The external magnetic field of H = 1000 Oe was applied parallel to the film surface along the longer dimension. The M – T data of all films is plotted in Fig. 4 (a-d). The behavior of the M – T curves around room temperature shows that all films have Curie transition above room temperature. We tried to extrapolate the M – T data to have an idea of the possible Curie T C values. The extrapolated values of the T C ~316 K, ~ 320 K, and 344 K for the films grown at 500 °C (5C), 600 °C (6C), and 700 °C (7C), respectively. The extrapolated T C of the film grown at 800 °C is ~ 337 K but given the nature of the M-T curve which has the signature of another transition around ~ 280 K, is not unambiguous. The other noteworthy features of the M – T data of the films grown at 500 °C, 600 °C, and 700 °C, are (i) an increase in the magnetic moment with the growth temperature, (ii) shrinkage of the ZFC-FCW divergence, and (iii) weakening and shifting of the downturn in the magnetization to lower temperatures. The ZFC-FCW divergence suggests the presence of a magnetically inhomogeneous state in the material which could be either due to (i) chemical inhomogeneity in the compound, or due to (ii) the presence of competing interactions or different sublattice alignments. Chemical inhomogeneity could arise due to intergranular variation in the chemical composition, which we have observed in the present case. The magnetization downturn temperature decreases from ~ 60 K at 500 °C to ~ 17 K at 700 °C, and this feature vanishes in the film annealed at 800 °C. The sharp decrease in the difference between the FCW and ZFC magnetization, namely, \(\varDelta M={M}_{FCW}-{M}_{ZFC}\) magnetization of all films as a function of the measurement temperature is shown in Fig. 5 a, while the variation with the growth temperature is shown in Fig. 5 b. The observed extrapolated Curie temperatures of the films 5C, 6C, and 7C are generally higher than the Ni-Mn-Sn containing bulk alloys. The abnormal behavior of the film grown at 800 °C could be understood in terms of chemical changes that it has undergone due to higher temperature treatment. The presence of highly non-stoichiometric Heusler phase and secondary phases like DO 19 type Ni 3 Sn and Mn 3 Sn intermetallic could be the reason for lowering the magnetic moment and appearance of a phase transition-like feature at relatively higher magnetic moments. The low-temperature behavior of these films was examined by analyzing the magnetization data in terms of Bloch’s law [ 42 ] given by $${M}_{S}\left(T\right)={M}_{0}\left(1-B{T}^{\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}\right)$$ 1 The above law is an empirical one and describes the temperature dependence of the spontaneous magnetization of ferromagnetic materials at a temperature much lower than the T C (T < < T C ) in the strong ferromagnetic limit. In the above equation \({M}_{0}\) represents the spontaneous magnetization at absolute zero, and prefactor B is the Bloch constant related to the Curie temperature, T C . The \({M}_{S}\left(T\right)-{T}^{\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}\) plot along with the best fit is Fig. 6 . The M-T of the films grown at 500 °C (5C), 600 °C (6C), and 700 °C (7C) follows the Bloch law at T < 143 K, while the one grown at 800 °C, which undergoes phase degeneration seems to follow this law in the range 14 K-75 K. Thus, the behaviour of films 5C, 6C, and 7C resembles like a local magnetic moment system, which is critical to have spin polarization in the Heusler systems. In view of the recent report by Harikrishnan et al. [ 43 ], the divergence from linear behaviour at temperatures above 143 K suggests that the band gap responsible for high spin polarization in one of the spin channels might disappear above this temperature. In such a case, electrons could fill the empty states near the Fermi level (E F ). For film 8C, this behavior is completely absent, and linear behavior is observed in the temperature range of 14 K to 75 K. This suggests that phase degeneration destroys the half-metallic behavior in films grown at higher temperatures. To gain deeper insights into the electronic behavior of these films, we measured their temperature-dependent resistivity (ρ-T). The experimental ρ-T data is presented in Fig. 7 (a, b). At room temperature, the resistivity of the film grown at 500°C (5C) is the lowest, with ρ(300K) = 7.10 × 10⁻⁵ Ω-cm. This value increases by nearly an order of magnitude to 7.95 × 10⁻⁴ Ω-cm as the growth temperature is raised to 600°C. The film grown at 700°C (7C) has a slightly higher room temperature resistivity of 2.42 × 10⁻⁴ Ω-cm, which nearly triples to 6.76 × 10⁻⁴ Ω-cm for the film grown at 800°C (8C). All the films exhibit metallic behavior, albeit with different temperature dependencies. The 5C film shows the slowest decrease in resistivity with decreasing temperature, resulting in the largest residual resistivity ratio (RRR = ρ(5K)/ρ(300K)) of ≈1.17. This ratio increases to ≈1.51 and ≈1.64 for the films grown at 600°C (6C) and 700°C (7C), respectively. The gradual increase in the value of the RRR as the growth temperature increases from 500 °C to 700 °C shows that in these films the defect/impurity scattering decreases. Notably, the phase-degenerated film grown at 800°C (8C) displays the steepest decline in resistivity, achieving the highest RRR of ≈956.59, which is comparable to the RRR of pure nickel metal. This sharp decrease in resistivity supports the occurrence of phase degeneration in films grown at higher temperatures. The low and room temperature resistivity are dominated by defect/impurity scattering and electron-phonon scattering, respectively. To better understand the impact of growth temperature on the underlying transport mechanism in these thin films, we analyzed the ρ-T data. According to Matthiessen's rule, the total resistivity of ferromagnetic materials is influenced by several scattering mechanisms and can be expressed by the following equation: $$\rho \left(T\right)={\rho }_{0}+{\rho }_{e-ph}\left(T\right)+{\rho }_{sd}\left(T\right)$$ 2 Here, \({\rho }_{0}\) represents the temperature-independent residual resistivity due to carrier scattering from lattice defects and impurities. The second term, \({\rho }_{e-ph}\left(T\right)\) accounts for the electron-phonon (e-ph) scattering, which is linearly dependent on temperature. The third term, \({\rho }_{sd}\left(T\right)\) represents the spin-disordered scattering from electron-magnon interactions, which has a quadratic temperature dependence and is effective only in the ferromagnetic state (T < T C ) [ 44 , 45 ]. In a more detailed form, the total resistivity can be written as: $$\rho \left(T\right)={\rho }_{0}+{A}_{ph}T+{B}_{sd}{T}^{2}$$ 3 Here, \({A}_{ph}\) and \({B}_{sd}\) are coefficients corresponding to the electron-phonon scattering and spin-disordered scattering contributions, respectively, and do not depend on temperature. The ρ-T of film 5C and 6C were fitted satisfactorily with Eq. ( 3 ), but those of films 7C and 8C could not be fitted. In fact, in the case of films 7C and 8C, the coefficient \({A}_{ph}\) changes sign to negative. Because of the above and the fact that in the temperature regime, T < T C , the electron-phonon scattering may not be a significant contributor to the resistivity, we tried to fit the ρ-T using the truncated form of Eq. ( 3 ), viz.: $$\rho \left(T\right)={\rho }_{0}+{B}_{sd}{T}^{\alpha }$$ 4 The ρ-T data for films 5C, 6C, and 7C are well-fitted by the aforementioned equation. The best-fitting values of the exponent α are 1.34±0.01, 1.69±0.01, 2.00±0.02, and 2.82±0.02 for films grown at 500°C (5C), 600°C (6C), 700°C (7C), and 800°C (8C), respectively. The variation of the exponent with the growth temperature is shown in Fig. 7 . It has been reported that the resistivity of spin glasses follows a temperature dependence given by Eq. ( 4 ) with α = 1.5 [ 46 , 47 ]. Given that the ZFC-FCW (Zero Field Cooled-Field Cooled Warming) divergence is prominent in films 5C and 6C, and the values of the exponent are closer to α = 1.5, we believe that the magnetoelectrical behavior of these films resembles that of spin glasses. For film 7C, which exhibits (i) the largest value of the magnetic moment, (ii) the highest Curie transition, and (iii) a small ZFC-FCW divergence, the exponent value is α = 2. In ferromagnetic materials, electrons are also inelastically spin-flip scattered with the creation or annihilation of a magnon, leading to a temperature-dependent resistivity of the type \(\rho \left(T\right)\sim{T}^{2}\) [ 48 ]. The ρ-T of the film 8C best fits to Eq. ( 4 ) with abnormally large value of α = 2.82. However, a noticeable deviation in the temperature range of \(80 K<T<168 K\) is observed. Such drastic deviation in the ρ-T behavior also supports the phase-degenerated nature of the films grown at a higher temperature of 800 °C. Conclusions In the present study, we have successfully deposited Mn-Ni-Sn-based Heusler alloy thin films using UHV RF Magnetron sputtering on STO (001). We have studied the effect of deposition and annealing from 500 ℃ to 800 ℃ with the step of 100 ℃ on the structural, surface morphology, magnetic, and transport properties of thin films. The study demonstrates that growth temperature significantly influences the structural phases, morphology, magnetic properties, and transport behavior of Mn-Ni-Sn-based Heusler alloy thin films. Our study shows that for Mn 2 NiSn type inverse full Heusler films, the most suitable deposition and annealing temperatures are in the range 600–700 °C. Optimal properties for spintronic applications were observed in films grown at temperatures up to 700°C, whereas films grown at 800°C suffered from phase degeneration, leading to loss of desirable magnetic and half-metallic characteristics. Declarations Author Contribution Annu: Methodology, Formal Analysis, Investigation, Writing - Original Draft. Komal: Formal Analysis, Data Curation. Jai Dev: Data Curation. Pallavi: Investigation, Resources. Jai Shankar: Investigation, Resources. Praveen Kumar: Writing - Review & Editing, Resources. Hari Krishna: Conceptualization, Writing - Review & Editing, Supervision. All authors have given approval to the final version of the manuscript. Acknowledgments One of the authors, Annu Verma, would like to thank the Council of Scientific & Industrial Research (CSIR) for the financial support through the award of a Junior and senior research fellowship (Budget Head-90807). The growth facility has been supported by the CSIR project PSSC-0110. References C. Felser and A. Hirohata (Editors), Heusler Alloys: Properties, Growth, and Applications, Springer Series in Materials Science Vol. 222 , Springer, Germany (2016) F. Heusler, Verh. Dtsch. Phys. Ges. 12 219 (1903) P. J. Webster, Heusler alloys Contemporary Physics, 10(6), 559–577 (1969). A. Hirohata, M. Kikuchi, N. Tezuka, K. Inomata, J.S. Claydon, Y.B. Xu, and G. van der Laan, Current Opinion in Solid State and Materials Science 10 93–107 (2006) T. Graf, C. Felser and S.S.P. Parkins, Progress in Solid State Chemistry 39 1-50 (2011). Lukas Wollmann, Ajaya K. Nayak,2 Stuart S.P. Parkin, and Claudia Felser, Annual Review of Materials Research 47 , 247-270 (2017) C. Guillemard, S. Petit-Watelot, T. Devolder, L. Pasquier, P. Boulet, S. Migot, J. Ghanbaja, F. Bertran, S. Andrieu, J. Appl. Phys. 128 , 241102 (2020) Kelvin Elphick, William Frost, Marjan Samiepour, Takahide Kubota, Koki Takanashi, Hiroaki Sukegawa, Seiji Mitani & Atsufumi Hirohata, Science and Technology of Advanced Materials, 22 235–271 (2022) Claudia Felser, Lukas Wollmann, Stanislav Chadov, Gerhard H. Fecher, Stuart S. P. Parkin, APL Mater. 3 041518 (2015). I. Galanakis, Ph. Mavropoulos and P. H. Dederichs, J. Phys. D: Appl. Phys. 39 765–775 (2006) I. Galanakis, P. H. Dederichs, and N. Papanikolaou, Physical Review B 66 , 174429, (2002). A. Kazutaka, M. Yoshio, S. Yasunori, S. Masafumi, Journal of Physics: Condensed Matter 21, 064244, (2009). M. Yoshio, U. Hirohisa, O. Yoshihiro, N. Kazutaka, S. Masafumi, Journal of Physics: Condensed Matter 19, 365228, (2007). T. Krenke, M. Acet, E. F. Wassermann, X. Moya, L. Mañosa, and A. Planes, Phys Rev B 72 014412 (2005) A. Çakır, M. Acet and M. Farle, Phys. Rev. B 93 094411 (2016) S. Aksoy, M. Acet, P. P. Deen, L. Mañosa and A. Planes, Phys. Rev. B 79 , 212401 (2009). P. Entel, M. E. Gruner, D. Comtesse, V. V. Sokolovskiy and V. D. Buchelnikov, Phys. Status Solidi B, 251 , 2135 (2014). J. A. Monroe, J. E. Raymond, X. Xu, M. Nagasako, R. Kainuma, Y. I. Chumlyakov, R. Arroyave and I. Karaman, Acta Mater., 101 107–115 (2015). P. Entel, M. E. Gruner, M. Acet, A. Çakır, R. Arroyave, T. Duong, S. Sahoo, S. Fahler and V. V. Sokolovskiy, Energy Technol. 6 1478 (2018). V. V. Sokolovskiy, M. E. Gruner, P. Entel, M. Acet, A. Çakır, D. R. Baigutlin and V. D. Buchelnikov, Phys. Rev. Mater. 3 084413 (2019). Q. Gao, I. Opahle, O. Guteisch and H. Zhang, Acta Mater. 186 355 (2020). B. Schleicher, D. Klar, K. Ollefs, A. Diestel, D. Walecki, E. Weschke, L. Schultz, K. Nielsch, S. Fahler, H. Wende and M. E. Gruner, J. Phys. D: Appl. Phys. 50 465005 (2017) T. Krenke, A. Çakır, F. Scheibel, M. Acet and M. Farle, J. Appl. Phys., 120 243904 (2016). H.C. Xuan, K. X. Xie, D. H. Wang,Z. D. Han, C. L. Zhang, B. X. Gu, and Y. W. Du, Appl. Phys. Lett. 92 242506 (2008) B. Hernando, J. L. Sánchez Llamazares, J. D. Santos, Ll. Escoda, J. J. Suñol, R. Varga, D. Baldomir, and D. Serantes, Appl. Phys. Lett. 92 042504 (2008) P.J. Brown, A.P. Gandy, K. Ishida, R. Kainuma, T. Kanomata, K.-U. Neumann, K. Oikawa, B. Ouladdiaf, K.R.A. Ziebeck, J. Phys. Condens. Matter 18 2249 (2006). N. Singh, B. Borgohain, A.K. Srivastava, A. Dhar, H.K. Singh, Appl. Phys. A 122 237 (2016). B. Borgohain, P.K. Siwach, N. Singh, H.K. Singh, J. Magn. Magn. Mater. 454 13 (2018). Barsha Borgohaina, P.K. Siwach, Nidhi Singha, V.P.S. Awana, and H.K. Singh, Intermetallic 111 106492 (2019) U. Geiersbach, A. Bergmann, and K. Westerholt, J. Magn. Magn. Mater. 240, 546 (2002). M. S. Lund, J. W. Dong, J. Lu, X. Y. Dong, C. J. Palmstrøm, and C. Leighton, Appl. Phys. Lett. 80, 4798–4800 (2002) S. Kämmerer, A. Thomas, A. Hütten, and G. Reiss, Appl. Phys. Lett. 85 , 79–81 (2004) K. Inomata, S. Okamura, R. Goto and N. Tezuka, Jpn. J. Appl. Phys. 42 , L 419–L 422 (2003) S. Kämmerer, S. Heitmann, D. Meyners, D. Sudfeld, A. Thomas, A. Hütten, and G. Reiss, J. Appl. Phys. 93, 7945 (2003). L. J. Singh, Z. H. Barber, Y. Miyoshi, Y. Bugoslavsky, W. R. Branford, and L. F. Cohen. Appl. Phys. Lett. 84, 2367 (2004). L. J. Singh, Z. H. Barber, Y. Miyoshi, W. R. Branford, and L. F. Cohen. J. Appl. Phys. 95, 7231 (2004). J. Dubowik, K. Załski, I. Gościańska, H. Głowiński, and A. Ehresmann, Appl. Phys. Lett. 100 , 162403 (2012) Ritu Vishnoi and Davinder Kaur, J. Appl. Phys. 107 , 103907 (2010) Ritu Vishnoi and Davinder Kaur, Journal of Alloys and Compounds 509 2833 (2011) Barsha Borgohain, P. K. Siwach & Nidhi Singh, K. V. R. Rao and H. K. Singh, Journal of Superconductivity and Novel Magnetism 32 3295 (2019) H. Ahmed, H. C. Kandpal, and P. C. Patel, J. Electronic Mater. 48 7944 (2019). Neil Ashcroft and N. D. Mermin, Solid State Physics, Academic Press, New York (1976). R. Harikrishnan, Jatin Kumar Bidika, B. R. K. Nanda, A. J. Chelvane, S. D. Kaushik, P. D. Babu, and Harish Kumar Narayanan, Phys. Rev. B 108 , 094407 (2023). T. Fiji, J. of the Japan Institute of Metals and Materials 34(4):456-459 (2008). W.H. Schreiner, P. Pureur, D.E. Brandão, Electrical resistivity of the Pd‐based Heusler alloys, Phys. Status Solidi 60 K123–K126 (1980). S. Chakraborty, and A.K. Majumdar, Phys. Rev. B 53 6235 (1996). N. Rivier, and K. Adkins, J. Phys. F Met. Phys. 5 1745 (1975). P. V. Prakash Madduri and S. N. Kaul, Phys. Rev. B 95 , 184402 (2017). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4540219","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":314938670,"identity":"13181ee2-b235-4568-9f8e-895dd142203a","order_by":0,"name":"Annu Verma","email":"","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":false,"prefix":"","firstName":"Annu","middleName":"","lastName":"Verma","suffix":""},{"id":314938672,"identity":"e8f084f6-78a0-4673-8e56-196b1cd33230","order_by":1,"name":"Komal Bhatt","email":"","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":false,"prefix":"","firstName":"Komal","middleName":"","lastName":"Bhatt","suffix":""},{"id":314938675,"identity":"b8406ccb-e17b-45b0-9904-efad4bc8b66c","order_by":2,"name":"Jai Dev Tanwar","email":"","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":false,"prefix":"","firstName":"Jai","middleName":"Dev","lastName":"Tanwar","suffix":""},{"id":314938676,"identity":"74083774-78b7-4c1d-be14-a08ae1246b76","order_by":3,"name":"Pallavi Kushwaha","email":"","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":false,"prefix":"","firstName":"Pallavi","middleName":"","lastName":"Kushwaha","suffix":""},{"id":314938677,"identity":"f1c3d8eb-9670-46fe-937a-6b486a29546a","order_by":4,"name":"Jai Shankar Tawale","email":"","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":false,"prefix":"","firstName":"Jai","middleName":"Shankar","lastName":"Tawale","suffix":""},{"id":314938678,"identity":"cb8197b3-c74b-45b8-addf-be53dc4dc29c","order_by":5,"name":"Praveen Kumar Siwach","email":"","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":false,"prefix":"","firstName":"Praveen","middleName":"Kumar","lastName":"Siwach","suffix":""},{"id":314938679,"identity":"40cb2bb3-a7c7-477d-b9bc-0fa473b1c9cc","order_by":6,"name":"Hari Krishna Singh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYBACAx4Gxsc/KhgY+JgZGCQSiNTCbMxwhoGBjRQtbMKMbUAtQI4EUQ4z5zn+jLlw3p08Nnbegzce1DDImfcvwK/FsrfH7PHMbc+K2Zj5ki0SjjEYy9x4QMBh53nYDXi3HU5sY+Yxk0hgY0icIXGAkBb2ZxK8c2Ba/hGj5WyDmTRvA1RLYhtQC38DAS1nzhgbzjh2GOgXHmOLxD4JYwlC4WZwJv3hgw81h/P4+c8Y3vzxzUZOgp+Aw2AgAUpLEBuhCC1AQKwto2AUjIJRMGIAACImQEjpVT+JAAAAAElFTkSuQmCC","orcid":"","institution":"CSIR National Physical Laboratory of India","correspondingAuthor":true,"prefix":"","firstName":"Hari","middleName":"Krishna","lastName":"Singh","suffix":""}],"badges":[],"createdAt":"2024-06-06 12:06:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4540219/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4540219/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":59215977,"identity":"7e62d1ce-2830-4678-9433-e918632704ba","added_by":"auto","created_at":"2024-06-27 19:00:41","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":131688,"visible":true,"origin":"","legend":"\u003cp\u003eThe XRR pattern of film deposited for 2 minutes and annealed at 700 °C for 6 hr.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/27a69572117c2c09831e05d9.png"},{"id":59215945,"identity":"75e3b793-f06a-472e-b9e4-346661fc185a","added_by":"auto","created_at":"2024-06-27 19:00:40","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":565356,"visible":true,"origin":"","legend":"\u003cp\u003eRoom temperature powder XRD patterns (upper panels of each figure) and HRXRD (lower panels of a-d) of Mn\u003csub\u003e2\u003c/sub\u003eNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e thin films on (001)-oriented STO substrates grown at 500 °C (a), 600 °C (b), 700 °C (c), and 800 °C (d). The impurity peaks are marked by asterisks.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/eae63df6f0f1593c8b349083.png"},{"id":59215974,"identity":"23b5d395-7f83-4b9c-9285-ffa337786b15","added_by":"auto","created_at":"2024-06-27 19:00:40","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":515010,"visible":true,"origin":"","legend":"\u003cp\u003eThe FESEM micrographs showing the representative surface morphologies of the Mn\u003csub\u003e2\u003c/sub\u003eNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e thin films grown at 500 °C (a), 600 °C (b), 700 °C (c), and 800 °C (d).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/23c6af4901e1c12bfcaa3ea6.png"},{"id":59215944,"identity":"4916a5f6-21dd-4649-b56d-ad7e33d0083a","added_by":"auto","created_at":"2024-06-27 19:00:40","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":460576,"visible":true,"origin":"","legend":"\u003cp\u003eThe temperature-dependent magnetization of Mn\u003csub\u003e2\u003c/sub\u003eNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e thin films grown at 500 °C (a), 600 °C (b), 700 °C (c), and 800 °C (d).\u0026nbsp; The magnetization was measured at an external magnetic field of H=1000 Oe.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/07b22294021e08e337a7dd85.png"},{"id":59215975,"identity":"7578c8da-7647-4273-8a24-19888d956d87","added_by":"auto","created_at":"2024-06-27 19:00:41","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":257941,"visible":true,"origin":"","legend":"\u003cp\u003eThe difference between the FCW and ZFC magnetization, namely, ∆M=MFCW-MZFC as a function of temperature (a) and as a function of the film growth temperature (b).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/c2adddbadb854dfa73ade715.png"},{"id":59215976,"identity":"83cad36c-d0c6-40ce-bafc-f521cd915bc9","added_by":"auto","created_at":"2024-06-27 19:00:41","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":250555,"visible":true,"origin":"","legend":"\u003cp\u003eThe M-T\u003csup\u003e3/2\u003c/sup\u003e plot of the lower temperature (T\u0026lt;\u0026lt;T\u003csub\u003eC\u003c/sub\u003e) magnetization of films grown at 500 °C and 800 °C (a) and 600 °C and 700 °C (b). The solid lines are the best fit to the experimental data (symbols).\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/bba94db19706144a344dd457.png"},{"id":59215973,"identity":"4b9c530d-5e2d-4a38-8063-5408a6c75d29","added_by":"auto","created_at":"2024-06-27 19:00:40","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":129607,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/b25812a995b0c28ba12f592b.png"},{"id":62141904,"identity":"fa791d50-bebb-491a-a43f-bff68c71cb27","added_by":"auto","created_at":"2024-08-09 17:32:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2533058,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4540219/v1/5d0af01a-962f-46d9-b1a5-30c1f8d6a7e4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Microstructure, Magnetism and Electrical Transport Properties of Mn-Ni-Sn based Heusler Alloy Thin Films Grown Using RF Magnetron Sputtering: Consequences of Annealing Conditions","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHeusler alloys are a unique class of materials that can possess ferromagnetism with Curie temperature distributed over a wide temperature range of 200 K to 1200 K despite having all non-magnetic constituents [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In 1903, Fritz Heusler, while working on a compound composed of Cu, Mn, and Al, having the chemical composition Cu\u003csub\u003e2\u003c/sub\u003eMnAl, found out that it is ferromagnetic, although none of the constituents was magnetic by itself [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Since then, thousands of member alloys have been added to the Heusler family. The different aspects of Heusler systems have been reviewed over the years [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR4 CR5 CR6 CR7 CR8\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Structural strangeness is one of the major sources of the unique and diversified properties of these alloys. If X and Y are transition elements and Z is a main group element, the ratio XYZ\u0026thinsp;=\u0026thinsp;1:1:1 is classified as the half Heusler variant, while the ratio XYZ\u0026thinsp;=\u0026thinsp;2:1:1 represents the full Heusler family. The X\u003csub\u003e2\u003c/sub\u003eYZ crystallizes into the cubic L2\u003csub\u003e1\u003c/sub\u003e structure formed by four interpenetrating fcc sublattices; the atomic sites (tetrahedral sites) of the two sublattices are filled equally by the X element and the atomic sites of the other two (octahedral sites) are occupied by the Y and Z elements. The ordering of the different elements occupying different atomic positions is the key to the magnetic and electronic properties of these materials. The presence of disorder may cause structural transformations, e.g., the interstitial disordering of Y and Z sites yields the B2 cubic structural phase. Magnetism originates from the complex hybridization of the orbitals of the different constituents. The hybridization of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({d}_{{z}^{2}}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({d}_{{x}^{2}-{y}^{2}}\\)\u003c/span\u003e\u003c/span\u003e yields a low-energy bonding \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({e}_{g}\\)\u003c/span\u003e\u003c/span\u003e orbital and a high-energy antibonding \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({e}_{u}\\)\u003c/span\u003e\u003c/span\u003e orbital. The hybridization of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({d}_{xy}\\)\u003c/span\u003e\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({d}_{yz}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({d}_{zx}\\)\u003c/span\u003e\u003c/span\u003e form a triply degenerate low-energy bonding \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({t}_{2g}\\)\u003c/span\u003e\u003c/span\u003e orbital and a triply degenerate high-energy antibonding \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({t}_{1u}\\)\u003c/span\u003e\u003c/span\u003eorbital [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Disorders in any form like chemical non-stoichiometry, interstitial disordering, changes in structure and atomic position swaps, modify the hybridization and hence the band structure. The effect of disorder on the half-metallic behavior is stronger than the structural changes as the minority spin band gap is sensitive to the local changes in hybridization. The magneto-electronic properties of Heusler materials are also impacted by heterointerfacing as it also changes the local hybridization in the proximity of the interfaces [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eNi-Mn-based full Heusler alloys, e.g., Ni\u003csub\u003e2\u003c/sub\u003eMnSn, Ni\u003csub\u003e2\u003c/sub\u003eMnGa, Ni\u003csub\u003e2\u003c/sub\u003eMnIn, Mn\u003csub\u003e2\u003c/sub\u003eNiSn, and their various substitutional variants have attained a special standing because of the occurrence of (i) austenite-martensite (AP-MP) transitions, (ii) intrinsic exchange bias, (iii) magnetocaloric effect, (iv) spin glass behavior and (v) magnetic anisotropy [\u003cspan additionalcitationids=\"CR15 CR16 CR17 CR18 CR19 CR20 CR21 CR22 CR23 CR24\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. One of the interesting aspects of these alloys is the existence of mixed antiferromagnetic (AFM) and ferromagnetic (FM) interactions, and the interplay between them determines the magnetoelectrical phase profile. A T\u003csub\u003eC\u003c/sub\u003e of T\u003csub\u003eC\u003c/sub\u003e~319 K with a cubic L2\u003csub\u003e1\u003c/sub\u003e structure and a magneto-structural (MS) phase transition at T\u003csub\u003eAM\u003c/sub\u003e=221 K during the cooling cycle and T\u003csub\u003eMA\u003c/sub\u003e=239 K in the warming cycle was reported by Brown and coworkers in Ni\u003csub\u003e2\u003c/sub\u003eMn\u003csub\u003e1.44\u003c/sub\u003eSn\u003csub\u003e0.56\u003c/sub\u003e [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The MS transitions are very sensitive to subtle changes in the chemical compositions and post-annealing. The importance of the Heusler alloys was demonstrated by the recent observation of the shell-ferromagnetic effect in Mn-rich AFM Heusler systems Ni\u003csub\u003e50\u003c/sub\u003eMn\u003csub\u003e45\u003c/sub\u003eZ\u003csub\u003e5\u003c/sub\u003e (Z: Al, Ga, In, Sn, Sb) [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This effect occurs when the L2\u003csub\u003e1\u003c/sub\u003e-FM alloy with composition Ni\u003csub\u003e50\u003c/sub\u003eMn\u003csub\u003e25\u003c/sub\u003eZ\u003csub\u003e25\u003c/sub\u003e and AFM-L1\u003csub\u003e0\u003c/sub\u003e Ni\u003csub\u003e50\u003c/sub\u003eMn\u003csub\u003e50\u003c/sub\u003e coexist on annealing in the temperature range\u0026thinsp;~\u0026thinsp;350\u0026ndash;500 \u0026deg;C. The MS transitions, spin glass behavior, and the re-entrant ferromagnetism in the martensite state have also been demonstrated in the inverse Heusler alloy Mn\u003csub\u003e2\u003c/sub\u003eNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e and its Cr-doped versions [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Small variations in the Mn/Ni ratio shift the T\u003csub\u003eAM\u003c/sub\u003e and T\u003csub\u003eC\u003c/sub\u003e to higher temperatures, cause hysteresis in resistivity and magnetization, and transform the low-temperature cluster glass into spin glass [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Thus, the inverse Heusler variants also offer an interesting area of investigation.\u003c/p\u003e \u003cp\u003eThe studies on Heusler alloy films are scarce, and those on Ni-Mn-Sn-containing compounds are very few. The studies on Heusler thin films are constrained by issues related to the control of the chemical constitution. Since thin films are important for electronic and spintronic applications in contemporary technology, the development of synthesis and annealing protocols that lead to the precise control of chemical composition and, hence, optimum and stable magnetic properties are warranted. Lund et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] used MBE to grow epitaxial films of Ni\u003csub\u003e2\u003c/sub\u003eMnGa, Ni\u003csub\u003e2\u003c/sub\u003eMnGe, and Ni\u003csub\u003e2\u003c/sub\u003eMnAl on (001) oriented GaAs, with the first two alloys had the Curie temperature of T\u003csub\u003eC\u003c/sub\u003e~340 K and ~\u0026thinsp;300 K, respectively. The ρ-T of the FM of Ni\u003csub\u003e2\u003c/sub\u003eMnGa and Ni\u003csub\u003e2\u003c/sub\u003eMnGe alloys showed a peak and maximum negative MR near T\u003csub\u003eC\u003c/sub\u003e. A crossover from metallic to semiconducting behavior and the low-temperature resistivity upturn marks the unconventional metallic nature of these alloys. Co-Mn-based alloys, e.g., Co\u003csub\u003e2\u003c/sub\u003eMnSi, Co\u003csub\u003e2\u003c/sub\u003eMnSn, Co\u003csub\u003e2\u003c/sub\u003eMnAl, and Co\u003csub\u003e2\u003c/sub\u003eFeAl have been investigated by several groups over the past two decades [\u003cspan additionalcitationids=\"CR32 CR33 CR34 CR35\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Single-phase thin films of Co-Mn-based half-metallic Heusler compounds, namely Co\u003csub\u003e2\u003c/sub\u003eMnSi, Co\u003csub\u003e2\u003c/sub\u003eMnGe, and Co\u003csub\u003e2\u003c/sub\u003eMnSn (i) with the ordered L2\u003csub\u003e1\u003c/sub\u003e structure, (ii) very smooth surface morphology and (iii) pronounced (110) texture was deposited by RF magnetron sputtering on sapphire a-plane and (100)-MgO [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Fe-site Cr substituted Co\u003csub\u003e2\u003c/sub\u003eFeAl Heusler alloy film having a B2 structure on thermally oxidized Si had a magnetic moment of 2.04 \u0026micro;\u003csub\u003eB\u003c/sub\u003e/fu, suggesting a localized nature of ferromagnetism, which is a necessary condition for half metallicity [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Cu\u003csub\u003e2\u003c/sub\u003eMnAl and Co\u003csub\u003e2\u003c/sub\u003eMnSi films grown at low temperatures (~\u0026thinsp;150\u0026ndash;200 \u0026deg;C), are paramagnetic (PM) and had higher resistivity (~\u0026thinsp;100\u0026ndash;200 \u0026micro;Ω-cm), while those grown at higher temperatures had lower resistivity and were FM, with T\u003csub\u003eC\u003c/sub\u003e~600 \u0026deg;C and ~\u0026thinsp;950 \u0026deg;C [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. The temperature-dependent resistivity (ρ-T) followed a \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\rho \\left(T\\right)\\simT\\)\u003c/span\u003e\u003c/span\u003e dependence in the range 300 K-100 K, while at T\u0026lt;100 K, it followed \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\rho \\left(T\\right)\\sim{T}^{2}+{T}^{\\raisebox{1ex}{$9$}\\!\\left/ \\!\\raisebox{-1ex}{$2$}\\right.}\\)\u003c/span\u003e\u003c/span\u003e. Here, the first term denotes either the one-magnon (1m) scattering or the electron-electron (e-e) scattering, and the second term accounts for the two-magnon (2m) scattering [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. J. Dubowik et al. [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e] magnetron sputtered Ni\u003csub\u003e50\u003c/sub\u003eMn\u003csub\u003e35\u003c/sub\u003eSn\u003csub\u003e15\u003c/sub\u003e (Ni\u003csub\u003e2\u003c/sub\u003eMn\u003csub\u003e1.4\u003c/sub\u003eSn\u003csub\u003e0.6\u003c/sub\u003e) thin films on (001)-MgO substrates at 350 \u0026deg;C at 2 mTorr of Ar pressure and annealed them at 800 \u0026deg;C to achieve structural ordering. These films are chemically ordered with (00l) oriented with lattice constant a=0.598 nm but magnetically inhomogeneous with the AFM order extending into the austenite phase. About 30% lower magnetic moment in the MP than that in AP was attributed to the decrease in the Mn-Mn distance. Vishnoi and Kaur performed several studies on about 1 \u0026micro;m thick Ni\u003csub\u003e50\u003c/sub\u003eMn\u003csub\u003e50\u0026minus;x\u003c/sub\u003eSn\u003csub\u003ex\u003c/sub\u003e (x=15,16, 18, 22) films on Si substrate [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Ni\u003csub\u003e52.6\u003c/sub\u003eMn\u003csub\u003e23.7\u003c/sub\u003eSn\u003csub\u003e23.6\u003c/sub\u003e and Ni\u003csub\u003e51.5\u003c/sub\u003eMn\u003csub\u003e26.1\u003c/sub\u003eSn\u003csub\u003e22.2\u003c/sub\u003e films showed an austenite phase with a mixed L2\u003csub\u003e1\u003c/sub\u003e/A2+B2 structure. On the other hand, Ni\u003csub\u003e58.9\u003c/sub\u003eMn\u003csub\u003e28.0\u003c/sub\u003eSn\u003csub\u003e13.0\u003c/sub\u003e and Ni\u003csub\u003e58.3\u003c/sub\u003eMn\u003csub\u003e29.0\u003c/sub\u003eSn\u003csub\u003e12.6\u003c/sub\u003e films show a martensitic phase with a 14M modulated monoclinic structure. Substitution of Sn by Mn causes structural instability that, in turn, impacts the magnetic properties of these films [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Vishnoi and Kaur [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] have also reported the exchange bias effect in the martensitic state of Ni\u003csub\u003e49.8\u003c/sub\u003eMn\u003csub\u003e36.1\u003c/sub\u003eSn\u003csub\u003e13.9\u003c/sub\u003e film. They attributed it to the unidirectional anisotropy that arises due to the coupling between AFM and FM interactions in the martensite phase of the film. Barsha Borgohain et al. [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e] have investigated 400 nm thick Ni\u003csub\u003e51\u003c/sub\u003eMn\u003csub\u003e33\u003c/sub\u003eCr\u003csub\u003e5\u003c/sub\u003eSn\u003csub\u003e11\u003c/sub\u003e films deposited on (001)-MgO by dc magnetron sputtering and reported (i) enhanced T\u003csub\u003eC\u003c/sub\u003e~321 K, (ii) the occurrence of austenite-martensite transitions over a very broad range, (iii) exchange bias effect in lower temperature region.\u003c/p\u003e \u003cp\u003eThe above survey shows that very little work has been done on the Ni-Mn-X-based alloys. These alloy systems still lack an optimized growth and annealing protocol required to grow thin films that achieve desired properties reproducibly. In the current study, the effect of annealing up to a temperature of 800 ℃ on structural features, surface morphology, chemical composition, magnetic, and transport properties in off-stoichiometric Mn-Ni-Sn based Heusler alloy thin films. We have found that annealing at very high temperatures has a profound effect on the properties of the thin films.\u003c/p\u003e"},{"header":"Experimental Details","content":"\u003cp\u003eMn\u003csub\u003e2\u003c/sub\u003eNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e thin films were grown using an ultra-high vacuum (UHV) RF magnetron sputtering on (001)-oriented SrTiO\u003csub\u003e3\u003c/sub\u003e (STO) substrates. A commercially procured alloy target with a nominal composition of Mn\u003csub\u003e2\u003c/sub\u003eNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e and 2-inch in diameter was used for deposition. The target thickness was ~\u0026thinsp;3 mm. The target-to-substrate distance was fixed at ~\u0026thinsp;5 cm. The base pressure of the deposition chamber was 1.5\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e mTorr, and the depositions were carried out at the optimized Ar pressure of 2 mTorr. Before deposition, the substrates were cleaned thoroughly with boiled acetone then with isopropyl alcohol, and at last with deionized water. The substrate temperature (t\u003csub\u003eS\u003c/sub\u003e) was varied from 500 \u0026deg;C to 800 \u0026deg;C in the steps of 100 \u0026deg;C. During deposition, the substrate was rotated at a speed of 10 rpm to ensure deposition uniformity, and the RF power was maintained at 50 W. Pre-deposition sputtering was done for about fifteen minutes to ensure the same state of target at all depositions and removal of any impurities that can be present. The RF sputtering was done for 10 minutes. All the films were annealed in situ for six hours at the respective deposition temperatures. The thickness of the films was estimated by X-ray reflectivity (XRR), and the average deposition rate was estimated to be ~\u0026thinsp;3.6 nm/minute under the above-mentioned conditions. The structural characterization was done using a powder X-ray diffractometer with Cu K\u003csub\u003eα\u003c/sub\u003e radiation (Rigaku Ultima Ⅳ) and a high-resolution X-ray diffractometer employing Cu K\u003csub\u003eα1\u003c/sub\u003e radiation (PANalytical, X\u0026prime;Pert PRO MRD). A Quantum design magnetic property measurements system (MPMS) (MPMS XL 7) was used for magnetization measurements at a magnetic field of H\u0026thinsp;=\u0026thinsp;1000 Oe in the temperature range 5 K \u0026ndash; 300 K. The transport measurements were done in the four-probe linear contact geometry with the temperature ranging from 4.2 K to 300 K. A field emission scanning electron microscope (FESEM) (Zeiss EVO MA 10, Oxford INCA 250) equipped with energy dispersive spectroscopy (EDS) was used to estimate the chemical composition and surface morphology.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eFor the present study, we have chosen the films deposited for 10 minutes and annealed at the respective deposition temperatures for 6 hours in Ar ambient. The estimation of the film thickness was done by XRR. The XRR of films deposited for different durations under the same experimental conditions was done, and the film thickness was estimated using the formula \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(D=\\frac{m\\lambda }{2\\sqrt{{\\left(\\text{sin}{\\theta }_{i}\\right)}^{2}- {\\left(\\text{sin}{\\theta }_{c}\\right)}^{2}}}\\)\u003c/span\u003e\u003c/span\u003e where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\theta }}_{c}\\)\u003c/span\u003e\u003c/span\u003e is the critical angle and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\theta }}_{\\text{i}}\\)\u003c/span\u003e\u003c/span\u003e is the angle corresponding to the m\u003csup\u003eth\u003c/sup\u003e order Kiessig fringe. The representative XRR pattern of a film with a 2-minute deposition time is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The thickness of the film was ~\u0026thinsp;7.2 nm and this gives a deposition rate of ~\u0026thinsp;3.6 nm per minute. Thus, the approximate thickness of the present films is ~\u0026thinsp;40 nm.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe structural characterization was done by high resolution and powder x-ray diffractometry (HR-XRD and P-XRD) using CuK\u003csub\u003eα1\u003c/sub\u003e (1.5406 \u0026Aring;) and CuK\u003csub\u003eα\u003c/sub\u003e (1.5418 \u0026Aring;) radiations. The obtained powder and high-resolution XRD patterns are plotted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The P-XRD pattern of the film deposited and annealed at 500 \u0026deg;C (denoted by 5C) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea) shows the occurrence of the (200) superlattice reflections and the principal (400) reflections. This indicates the formation of an ordered B2 phase. In addition, the (220) is also present in the XRD pattern, which suggests the presence of the fcc L2\u003csub\u003e1\u003c/sub\u003e-type structure as well as the existence of a long-range atomic order. The second-order super lattice peak (222) is also present, and it supports the long-range order with the fcc L2\u003csub\u003e1\u003c/sub\u003e structure. However, in the case of B2 type structure, which has a lesser degree of order than the L2\u003csub\u003e1\u003c/sub\u003e structure, the (222) may have a weaker presence than the (200) and (400) reflections or it may not appear at all. The HRXRD scan shows the occurrence of the (200) and (400) reflections. Thus, the film deposited and annealed at 500 \u0026deg;C has a mixture of the B2 and L2\u003csub\u003e1\u003c/sub\u003e phases. As the growth temperature is increased from 500 \u0026deg;C to 600 \u0026deg;C (film denoted by 6C), the (220) and (222) diffraction maxima vanish (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb), and only (200) and (400) peaks appear in P-XRD as well as the HRXRD. The disappearance of (220) and (222) peaks shows the presence of the B2 phase due to the reduced atomic order. The film grown at a further higher temperature of 700 \u0026deg;C also shows similar structural features; however, the occurrence of a small but sharp peak at 2θ\u0026thinsp;=\u0026thinsp;41.76\u0026deg; indicates the presence of an impurity. A decomposition of the B2 Heusler structure is possible at higher growth temperatures. In Mn-Ni-Sn based Heusler systems the occurrence of impurity phases like Ni\u003csub\u003e3\u003c/sub\u003eSn or Mn\u003csub\u003e3\u003c/sub\u003eSn may take place due to non-stoichiometric growth conditions. The most plausible alloys in the present case seem to be Ni\u003csub\u003e3\u003c/sub\u003eSn and Mn\u003csub\u003e3\u003c/sub\u003eSn; both have dominant XRD peaks of around 2θ\u0026thinsp;=\u0026thinsp;41.76\u0026deg;. In the case of cubic Ni\u003csub\u003e3\u003c/sub\u003eSn and Mn\u003csub\u003e3\u003c/sub\u003eSn, the (021) peak appears around Ni\u003csub\u003e3\u003c/sub\u003eSn and Mn\u003csub\u003e3\u003c/sub\u003eSn around 2θ\u0026thinsp;=\u0026thinsp;41.76\u0026deg;. In the powder XRD pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed) of the film deposited and annealed at 800 \u0026deg;C (8C), the (200) and (400) peaks are observed. In addition, several diffraction maxima, mostly located between 40\u0026ndash;45\u0026deg;, are seen. As seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, these peaks are sharper and distinct from the peaks that characterize the cubic Heusler L2\u003csub\u003e1\u003c/sub\u003e or B2 phases. A closer look at the P-XRD pattern of the film grown at 800 \u0026deg;C shows that the additional peaks appearing at 2θ\u0026thinsp;=\u0026thinsp;34.2\u0026deg;, 39.46\u0026deg;, 41.8\u0026deg;, 42.62\u0026deg;, and 43.46\u0026deg; could belong to the Ni\u003csub\u003e3\u003c/sub\u003eSn phase having a closest packed hexagonal structure (space group \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(P{6}_{3}/mmc\\)\u003c/span\u003e\u003c/span\u003e) and lattice constants a\u0026thinsp;=\u0026thinsp;5.296 \u0026Aring; and c\u0026thinsp;=\u0026thinsp;4.248 \u0026Aring; [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. The formation of the phase is driven by the evaporation of Mn due to the higher growth and annealing temperature of 800 \u0026deg;C. As discussed above the alloys Ni\u003csub\u003e3\u003c/sub\u003eSn or Mn\u003csub\u003e3\u003c/sub\u003eSn could appear as the impurity phases due to the thermally activated decomposition of the parent Heusler phase. The out-of-plane lattice constants of the films grown at 500 \u0026deg;C, 600 \u0026deg;C, 700 \u0026deg;C, and 800 \u0026deg;C are found to be 6.165 \u0026Aring;, 5.998 \u0026Aring;, 5.984 \u0026Aring; and 6.015 \u0026Aring;, respectively. The increase in the lattice constant of the film grown at 800 \u0026deg;C could be due to the chemical inhomogeneity and formation of secondary phases.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe chemical composition of all four films was examined by EDS attached to FESEM. The EDS spectra were recorded from five places in each film and the average composition was determined. Representative FESEM pictures of all films at the same magnification are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. It can be seen in the images that the surface microstructure consists of two phases: darker region and bright particles spread over the film surface. As seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, the surface morphology of the films grown at 500 \u0026deg;C is mostly continuous, and small particles are distributed over the surface sporadically. The overall composition of the film is Mn\u003csub\u003e2.16\u003c/sub\u003eNi\u003csub\u003e1.56\u003c/sub\u003eSn\u003csub\u003e0.30\u003c/sub\u003e. The bright particles over the film surface seem to come out of the film due to thermal stresses due to the thermal expansion coefficient mismatch between the film and the substrate STO. An increase in the film growth temperature has a degenerative influence on the surface morphology. In the film grown at 600 ℃, the continuity of the darker regions is disrupted, and the brighter particles appear to increase in size as well as density. The average chemical composition of the majority darker region of this film is Mn\u003csub\u003e2.10\u003c/sub\u003eNi\u003csub\u003e1.56\u003c/sub\u003eSn\u003csub\u003e0.34\u003c/sub\u003e. The brighter particles are nearly equiatomic in Mn and Ni but very low in Sn content. Since the particles are distantly placed, the transport behavior is not expected to be affected much by them. However, their chemical composition may have an impact on the magnetic characteristics. The surface morphology of the film grown at 700 \u0026deg;C is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec. Most of the surface still consists of the dark layer; however, the layer itself becomes more discontinuous. As a result, the bright particles become larger and higher in number density. The average composition of the darker layer is Mn\u003csub\u003e1.9\u003c/sub\u003eNi\u003csub\u003e1.66\u003c/sub\u003eSn\u003csub\u003e0.43\u003c/sub\u003e, while the brighter regions remain nearly equiatomic in Mn and Ni and low in Sn content. Thus, the film grown at 700 \u0026deg;C shows an Mn deficient Heusler phase but also has Ni\u003csub\u003e3\u003c/sub\u003eSn and Mn\u003csub\u003e3\u003c/sub\u003eSn as the impurity phases. Growth temperature higher than 700 \u0026deg;C leads to an enhancement in the number-density and size of the bright particles which, become dominant in the surface morphology. The average composition of these particles is Mn\u003csub\u003e0.21\u003c/sub\u003eNi\u003csub\u003e2.98\u003c/sub\u003eSn\u003csub\u003e0.81\u003c/sub\u003e suggesting the formation Ni\u003csub\u003e3\u003c/sub\u003eSn majority and Mn\u003csub\u003e3\u003c/sub\u003eSn minority phases. The dark regions look highly disrupted, and their average composition is Mn\u003csub\u003e0.91\u003c/sub\u003eNi\u003csub\u003e2.76\u003c/sub\u003eSn\u003csub\u003e0.33\u003c/sub\u003e. Thus, higher temperature growth, e.g., at 700 \u0026deg;C and 800 \u0026deg;C is not conducive to the stability of the Heusler phases.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe temperature dependence of magnetization (M \u0026ndash; T) was measured in the temperature range of 300 K\u0026ndash; 5 K in the zero-field cooled (ZFC), field-cooled cooling (FCC), and field-cooled warming (FCW). The external magnetic field of H\u0026thinsp;=\u0026thinsp;1000 Oe was applied parallel to the film surface along the longer dimension. The M \u0026ndash; T data of all films is plotted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e (a-d). The behavior of the M \u0026ndash; T curves around room temperature shows that all films have Curie transition above room temperature. We tried to extrapolate the M \u0026ndash; T data to have an idea of the possible Curie T\u003csub\u003eC\u003c/sub\u003e values. The extrapolated values of the T\u003csub\u003eC\u003c/sub\u003e ~316 K, ~\u0026thinsp;320 K, and 344 K for the films grown at 500 \u0026deg;C (5C), 600 \u0026deg;C (6C), and 700 \u0026deg;C (7C), respectively. The extrapolated T\u003csub\u003eC\u003c/sub\u003e of the film grown at 800 \u0026deg;C is ~\u0026thinsp;337 K but given the nature of the M-T curve which has the signature of another transition around ~\u0026thinsp;280 K, is not unambiguous. The other noteworthy features of the M \u0026ndash; T data of the films grown at 500 \u0026deg;C, 600 \u0026deg;C, and 700 \u0026deg;C, are (i) an increase in the magnetic moment with the growth temperature, (ii) shrinkage of the ZFC-FCW divergence, and (iii) weakening and shifting of the downturn in the magnetization to lower temperatures.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe ZFC-FCW divergence suggests the presence of a magnetically inhomogeneous state in the material which could be either due to (i) chemical inhomogeneity in the compound, or due to (ii) the presence of competing interactions or different sublattice alignments. Chemical inhomogeneity could arise due to intergranular variation in the chemical composition, which we have observed in the present case. The magnetization downturn temperature decreases from ~\u0026thinsp;60 K at 500 \u0026deg;C to ~\u0026thinsp;17 K at 700 \u0026deg;C, and this feature vanishes in the film annealed at 800 \u0026deg;C. The sharp decrease in the difference between the FCW and ZFC magnetization, namely, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta M={M}_{FCW}-{M}_{ZFC}\\)\u003c/span\u003e\u003c/span\u003e magnetization of all films as a function of the measurement temperature is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, while the variation with the growth temperature is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe observed extrapolated Curie temperatures of the films 5C, 6C, and 7C are generally higher than the Ni-Mn-Sn containing bulk alloys. The abnormal behavior of the film grown at 800 \u0026deg;C could be understood in terms of chemical changes that it has undergone due to higher temperature treatment. The presence of highly non-stoichiometric Heusler phase and secondary phases like DO\u003csub\u003e19\u003c/sub\u003e type Ni\u003csub\u003e3\u003c/sub\u003eSn and Mn\u003csub\u003e3\u003c/sub\u003eSn intermetallic could be the reason for lowering the magnetic moment and appearance of a phase transition-like feature at relatively higher magnetic moments. The low-temperature behavior of these films was examined by analyzing the magnetization data in terms of Bloch\u0026rsquo;s law [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e] given by\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${M}_{S}\\left(T\\right)={M}_{0}\\left(1-B{T}^{\\raisebox{1ex}{$3$}\\!\\left/ \\!\\raisebox{-1ex}{$2$}\\right.}\\right)$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe above law is an empirical one and describes the temperature dependence of the spontaneous magnetization of ferromagnetic materials at a temperature much lower than the T\u003csub\u003eC\u003c/sub\u003e (T\u0026thinsp;\u0026lt;\u0026thinsp;\u0026lt;\u0026thinsp;T\u003csub\u003eC\u003c/sub\u003e) in the strong ferromagnetic limit. In the above equation \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({M}_{0}\\)\u003c/span\u003e\u003c/span\u003e represents the spontaneous magnetization at absolute zero, and prefactor B is the Bloch constant related to the Curie temperature, T\u003csub\u003eC\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({M}_{S}\\left(T\\right)-{T}^{\\raisebox{1ex}{$3$}\\!\\left/ \\!\\raisebox{-1ex}{$2$}\\right.}\\)\u003c/span\u003e\u003c/span\u003e plot along with the best fit is Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The M-T of the films grown at 500 \u0026deg;C (5C), 600 \u0026deg;C (6C), and 700 \u0026deg;C (7C) follows the Bloch law at T\u0026thinsp;\u0026lt;\u0026thinsp;143 K, while the one grown at 800 \u0026deg;C, which undergoes phase degeneration seems to follow this law in the range 14 K-75 K. Thus, the behaviour of films 5C, 6C, and 7C resembles like a local magnetic moment system, which is critical to have spin polarization in the Heusler systems. In view of the recent report by Harikrishnan et al. [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], the divergence from linear behaviour at temperatures above 143 K suggests that the band gap responsible for high spin polarization in one of the spin channels might disappear above this temperature. In such a case, electrons could fill the empty states near the Fermi level (E\u003csub\u003eF\u003c/sub\u003e). For film 8C, this behavior is completely absent, and linear behavior is observed in the temperature range of 14 K to 75 K. This suggests that phase degeneration destroys the half-metallic behavior in films grown at higher temperatures.\u003c/p\u003e \u003cp\u003eTo gain deeper insights into the electronic behavior of these films, we measured their temperature-dependent resistivity (ρ-T). The experimental ρ-T data is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a, b). At room temperature, the resistivity of the film grown at 500\u0026deg;C (5C) is the lowest, with ρ(300K)\u0026thinsp;=\u0026thinsp;7.10 \u0026times; 10⁻⁵ Ω-cm. This value increases by nearly an order of magnitude to 7.95 \u0026times; 10⁻⁴ Ω-cm as the growth temperature is raised to 600\u0026deg;C. The film grown at 700\u0026deg;C (7C) has a slightly higher room temperature resistivity of 2.42 \u0026times; 10⁻⁴ Ω-cm, which nearly triples to 6.76 \u0026times; 10⁻⁴ Ω-cm for the film grown at 800\u0026deg;C (8C). All the films exhibit metallic behavior, albeit with different temperature dependencies. The 5C film shows the slowest decrease in resistivity with decreasing temperature, resulting in the largest residual resistivity ratio (RRR\u0026thinsp;=\u0026thinsp;ρ(5K)/ρ(300K)) of \u0026asymp;1.17. This ratio increases to \u0026asymp;1.51 and \u0026asymp;1.64 for the films grown at 600\u0026deg;C (6C) and 700\u0026deg;C (7C), respectively. The gradual increase in the value of the RRR as the growth temperature increases from 500 \u0026deg;C to 700 \u0026deg;C shows that in these films the defect/impurity scattering decreases. Notably, the phase-degenerated film grown at 800\u0026deg;C (8C) displays the steepest decline in resistivity, achieving the highest RRR of \u0026asymp;956.59, which is comparable to the RRR of pure nickel metal. This sharp decrease in resistivity supports the occurrence of phase degeneration in films grown at higher temperatures. The low and room temperature resistivity are dominated by defect/impurity scattering and electron-phonon scattering, respectively.\u003c/p\u003e \u003cp\u003eTo better understand the impact of growth temperature on the underlying transport mechanism in these thin films, we analyzed the ρ-T data. According to Matthiessen's rule, the total resistivity of ferromagnetic materials is influenced by several scattering mechanisms and can be expressed by the following equation:\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\rho \\left(T\\right)={\\rho }_{0}+{\\rho }_{e-ph}\\left(T\\right)+{\\rho }_{sd}\\left(T\\right)$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eHere, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\rho }_{0}\\)\u003c/span\u003e\u003c/span\u003e represents the temperature-independent residual resistivity due to carrier scattering from lattice defects and impurities. The second term, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\rho }_{e-ph}\\left(T\\right)\\)\u003c/span\u003e\u003c/span\u003e accounts for the electron-phonon (e-ph) scattering, which is linearly dependent on temperature. The third term, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\rho }_{sd}\\left(T\\right)\\)\u003c/span\u003e\u003c/span\u003e represents the spin-disordered scattering from electron-magnon interactions, which has a quadratic temperature dependence and is effective only in the ferromagnetic state (T\u0026thinsp;\u0026lt;\u0026thinsp;T\u003csub\u003eC\u003c/sub\u003e) [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. In a more detailed form, the total resistivity can be written as:\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\rho \\left(T\\right)={\\rho }_{0}+{A}_{ph}T+{B}_{sd}{T}^{2}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eHere, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({A}_{ph}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({B}_{sd}\\)\u003c/span\u003e\u003c/span\u003e are coefficients corresponding to the electron-phonon scattering and spin-disordered scattering contributions, respectively, and do not depend on temperature. The ρ-T of film 5C and 6C were fitted satisfactorily with Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), but those of films 7C and 8C could not be fitted. In fact, in the case of films 7C and 8C, the coefficient \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({A}_{ph}\\)\u003c/span\u003e\u003c/span\u003e changes sign to negative. Because of the above and the fact that in the temperature regime, T\u0026thinsp;\u0026lt;\u0026thinsp;T\u003csub\u003eC\u003c/sub\u003e, the electron-phonon scattering may not be a significant contributor to the resistivity, we tried to fit the ρ-T using the truncated form of Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), viz.:\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$$\\rho \\left(T\\right)={\\rho }_{0}+{B}_{sd}{T}^{\\alpha }$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe ρ-T data for films 5C, 6C, and 7C are well-fitted by the aforementioned equation. The best-fitting values of the exponent α are 1.34\u0026plusmn;0.01, 1.69\u0026plusmn;0.01, 2.00\u0026plusmn;0.02, and 2.82\u0026plusmn;0.02 for films grown at 500\u0026deg;C (5C), 600\u0026deg;C (6C), 700\u0026deg;C (7C), and 800\u0026deg;C (8C), respectively. The variation of the exponent with the growth temperature is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. It has been reported that the resistivity of spin glasses follows a temperature dependence given by Eq.\u0026nbsp;(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) with α\u0026thinsp;=\u0026thinsp;1.5 [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. Given that the ZFC-FCW (Zero Field Cooled-Field Cooled Warming) divergence is prominent in films 5C and 6C, and the values of the exponent are closer to α\u0026thinsp;=\u0026thinsp;1.5, we believe that the magnetoelectrical behavior of these films resembles that of spin glasses. For film 7C, which exhibits (i) the largest value of the magnetic moment, (ii) the highest Curie transition, and (iii) a small ZFC-FCW divergence, the exponent value is α\u0026thinsp;=\u0026thinsp;2. In ferromagnetic materials, electrons are also inelastically spin-flip scattered with the creation or annihilation of a magnon, leading to a temperature-dependent resistivity of the type \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\rho \\left(T\\right)\\sim{T}^{2}\\)\u003c/span\u003e\u003c/span\u003e [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. The ρ-T of the film 8C best fits to Eq.\u0026nbsp;(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) with abnormally large value of α\u0026thinsp;=\u0026thinsp;2.82. However, a noticeable deviation in the temperature range of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(80 K\u0026lt;T\u0026lt;168 K\\)\u003c/span\u003e\u003c/span\u003e is observed. Such drastic deviation in the ρ-T behavior also supports the phase-degenerated nature of the films grown at a higher temperature of 800 \u0026deg;C.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn the present study, we have successfully deposited Mn-Ni-Sn-based Heusler alloy thin films using UHV RF Magnetron sputtering on STO (001). We have studied the effect of deposition and annealing from 500 ℃ to 800 ℃ with the step of 100 ℃ on the structural, surface morphology, magnetic, and transport properties of thin films. The study demonstrates that growth temperature significantly influences the structural phases, morphology, magnetic properties, and transport behavior of Mn-Ni-Sn-based Heusler alloy thin films. Our study shows that for Mn\u003csub\u003e2\u003c/sub\u003eNiSn type inverse full Heusler films, the most suitable deposition and annealing temperatures are in the range 600\u0026ndash;700 \u0026deg;C. Optimal properties for spintronic applications were observed in films grown at temperatures up to 700\u0026deg;C, whereas films grown at 800\u0026deg;C suffered from phase degeneration, leading to loss of desirable magnetic and half-metallic characteristics.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAnnu: Methodology, Formal Analysis, Investigation, Writing - Original Draft. Komal: Formal Analysis, Data Curation. Jai Dev: Data Curation. Pallavi: Investigation, Resources. Jai Shankar: Investigation, Resources. Praveen Kumar: Writing - Review \u0026amp; Editing, Resources. Hari Krishna: Conceptualization, Writing - Review \u0026amp; Editing, Supervision. All authors have given approval to the final version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eOne of the authors, Annu Verma, would like to thank the Council of Scientific \u0026amp; Industrial Research (CSIR) for the financial support through the award of a Junior and senior research fellowship (Budget Head-90807). The growth facility has been supported by the CSIR project PSSC-0110.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eC. Felser and A. Hirohata (Editors), Heusler Alloys: Properties, Growth, and Applications, Springer Series in Materials Science Vol. \u003cstrong\u003e222\u003c/strong\u003e, Springer, Germany (2016)\u003c/li\u003e\n \u003cli\u003eF. Heusler, Verh. Dtsch. Phys. Ges. \u003cstrong\u003e12\u003c/strong\u003e 219 (1903)\u003c/li\u003e\n \u003cli\u003eP. J. Webster, Heusler alloys Contemporary Physics, 10(6), 559\u0026ndash;577 (1969).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eA. Hirohata, M. Kikuchi, N. Tezuka, K. Inomata, J.S. Claydon, Y.B. Xu, and G. van der Laan, Current Opinion in Solid State and Materials Science 10 93\u0026ndash;107 (2006)\u003c/li\u003e\n \u003cli\u003eT. Graf, C. Felser and S.S.P. Parkins, Progress in Solid State Chemistry 39 1-50 (2011).\u003c/li\u003e\n \u003cli\u003eLukas Wollmann, Ajaya K. Nayak,2 Stuart S.P. Parkin, and Claudia Felser, Annual Review of Materials Research \u003cstrong\u003e47\u003c/strong\u003e, 247-270 (2017)\u003c/li\u003e\n \u003cli\u003eC. Guillemard,\u0026nbsp;S. Petit-Watelot,\u0026nbsp;T. Devolder,\u0026nbsp;L. Pasquier,\u0026nbsp;P. Boulet,\u0026nbsp;S. Migot,\u0026nbsp;J. Ghanbaja,\u0026nbsp;F. Bertran,\u0026nbsp;S. Andrieu, J. Appl. Phys. \u003cstrong\u003e128\u003c/strong\u003e, 241102 (2020)\u003c/li\u003e\n \u003cli\u003eKelvin Elphick, William Frost, Marjan Samiepour, Takahide Kubota, Koki Takanashi, Hiroaki Sukegawa, Seiji Mitani \u0026amp; Atsufumi Hirohata, Science and Technology of Advanced Materials, \u003cstrong\u003e22\u003c/strong\u003e 235\u0026ndash;271 (2022)\u003c/li\u003e\n \u003cli\u003eClaudia Felser,\u0026nbsp;Lukas Wollmann,\u0026nbsp;Stanislav Chadov,\u0026nbsp;Gerhard H. Fecher,\u0026nbsp;Stuart S. P. Parkin, \u003cem\u003eAPL Mater.\u003c/em\u003e\u003cstrong\u003e3\u003c/strong\u003e 041518 (2015).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eI. Galanakis, Ph. Mavropoulos and P. H. Dederichs, J. Phys. D: Appl. Phys. \u003cstrong\u003e39\u003c/strong\u003e 765\u0026ndash;775 (2006)\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eI. Galanakis, P. H. Dederichs, and N. Papanikolaou, Physical Review B \u003cstrong\u003e66\u003c/strong\u003e, 174429, (2002).\u003c/li\u003e\n \u003cli\u003eA. Kazutaka, M. Yoshio, S. Yasunori, S. Masafumi, Journal of Physics: Condensed Matter 21, 064244, (2009).\u003c/li\u003e\n \u003cli\u003eM. Yoshio, U. Hirohisa, O. Yoshihiro, N. Kazutaka, S. Masafumi, Journal of Physics: Condensed Matter 19, 365228, (2007).\u003c/li\u003e\n \u003cli\u003eT. Krenke, M. Acet, E. F. Wassermann, X. Moya, L. Ma\u0026ntilde;osa, and A. Planes, \u0026nbsp;Phys Rev B \u003cstrong\u003e72\u003c/strong\u003e 014412 (2005)\u003c/li\u003e\n \u003cli\u003eA. \u0026Ccedil;akır, M. Acet and M. Farle, Phys. Rev. B \u003cstrong\u003e93\u003c/strong\u003e 094411 (2016)\u003c/li\u003e\n \u003cli\u003eS. Aksoy, M. Acet, P. P. Deen, L. Ma\u0026ntilde;osa and A. Planes, Phys. Rev. B \u003cstrong\u003e79\u003c/strong\u003e, 212401 (2009).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u0026nbsp;P. Entel, M. E. Gruner, D. Comtesse, V. V. Sokolovskiy and V. D. Buchelnikov, Phys.\u0026nbsp;Status Solidi B, \u003cstrong\u003e251\u003c/strong\u003e, 2135 (2014).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eJ. A. Monroe, J. E. Raymond, X. Xu, M. Nagasako, R. Kainuma, Y. I. Chumlyakov, R. Arroyave and I. Karaman, Acta Mater., \u003cstrong\u003e101\u003c/strong\u003e 107\u0026ndash;115 (2015).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eP. Entel, M. E. Gruner, M. Acet, A. \u0026Ccedil;akır, R. Arroyave, T. Duong, S. Sahoo, S. Fahler and V. V. Sokolovskiy, Energy Technol. \u003cstrong\u003e6\u003c/strong\u003e 1478 (2018).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eV. V. Sokolovskiy, M. E. Gruner, P. Entel, M. Acet, A. \u0026Ccedil;akır, D. R. Baigutlin and V. D. Buchelnikov, Phys. Rev. Mater. \u003cstrong\u003e3\u003c/strong\u003e 084413 (2019).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eQ. Gao, I. Opahle, O. Guteisch and H. Zhang, Acta Mater. \u003cstrong\u003e186\u003c/strong\u003e 355 (2020).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eB. Schleicher, D. Klar, K. Ollefs, A. Diestel, D. Walecki, E. Weschke, L. Schultz, K. Nielsch, S. Fahler, H. Wende and M. E. Gruner, J. Phys. D: Appl. Phys. \u003cstrong\u003e50\u003c/strong\u003e 465005 (2017)\u003c/li\u003e\n \u003cli\u003eT. Krenke, A. \u0026Ccedil;akır, F. Scheibel, M. Acet and M. Farle, J. Appl. Phys., \u003cstrong\u003e120\u003c/strong\u003e 243904 (2016).\u003c/li\u003e\n \u003cli\u003eH.C. Xuan, K. X. Xie, D. H. Wang,Z. D. Han, C. L. Zhang, B. X. Gu, and Y. W. Du, \u003cem\u003eAppl. Phys. Lett.\u003c/em\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003cstrong\u003e92\u003c/strong\u003e 242506 (2008)\u003c/li\u003e\n \u003cli\u003eB. Hernando, J. L. S\u0026aacute;nchez Llamazares, J. D. Santos, Ll. Escoda, J. J. Su\u0026ntilde;ol, R. Varga, D. Baldomir, and D. Serantes, Appl. Phys. Lett. \u003cstrong\u003e92\u003c/strong\u003e 042504 (2008)\u003c/li\u003e\n \u003cli\u003eP.J. Brown, A.P. Gandy, K. Ishida, R. Kainuma, T. Kanomata, K.-U. Neumann, K. Oikawa, B. Ouladdiaf, K.R.A. Ziebeck, J. Phys.\u0026nbsp;Condens. Matter \u003cstrong\u003e18\u003c/strong\u003e 2249 (2006).\u003c/li\u003e\n \u003cli\u003eN. Singh, B. Borgohain, A.K. Srivastava, A. Dhar, H.K. Singh, Appl. Phys. A \u003cstrong\u003e122\u003c/strong\u003e 237 (2016).\u003c/li\u003e\n \u003cli\u003eB. Borgohain, P.K. Siwach, N. Singh, H.K. Singh, J. Magn. Magn. Mater. \u003cstrong\u003e454\u0026nbsp;\u003c/strong\u003e13 (2018).\u003c/li\u003e\n \u003cli\u003eBarsha Borgohaina, P.K. Siwach, Nidhi Singha, V.P.S. Awana, and H.K. Singh, Intermetallic \u003cstrong\u003e111\u003c/strong\u003e 106492 (2019)\u003c/li\u003e\n \u003cli\u003eU. Geiersbach, A. Bergmann, and K. Westerholt, J. Magn. Magn. Mater. 240, 546 (2002).\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/li\u003e\n \u003cli\u003eM. S. Lund, J. W. Dong, J. Lu, X. Y. Dong, C. J. Palmstr\u0026oslash;m, and C. Leighton, Appl.\u0026nbsp;Phys. Lett. 80, 4798\u0026ndash;4800 (2002)\u003c/li\u003e\n \u003cli\u003eS. K\u0026auml;mmerer, A. Thomas, A. H\u0026uuml;tten, and G. Reiss, \u003cem\u003eAppl. Phys. Lett.\u003c/em\u003e\u003cstrong\u003e85\u003c/strong\u003e, 79\u0026ndash;81 (2004)\u003c/li\u003e\n \u003cli\u003eK. Inomata, S. Okamura, R. Goto and N. Tezuka, Jpn. J. Appl. Phys. \u003cstrong\u003e42\u003c/strong\u003e, L 419\u0026ndash;L 422 (2003)\u003c/li\u003e\n \u003cli\u003eS. K\u0026auml;mmerer, S. Heitmann, D. Meyners, D. Sudfeld, A. Thomas, A. H\u0026uuml;tten, and G. Reiss, J. Appl.\u0026nbsp;Phys. 93, 7945 (2003).\u003c/li\u003e\n \u003cli\u003eL. J. Singh, Z. H. Barber, Y. Miyoshi, Y. Bugoslavsky, W. R. Branford, and L. F. Cohen. Appl. Phys. Lett. 84, 2367 (2004).\u003c/li\u003e\n \u003cli\u003eL. J. Singh, Z. H. Barber, Y. Miyoshi, W. R. Branford, and L. F. Cohen. J. Appl. Phys. 95, 7231 (2004).\u003c/li\u003e\n \u003cli\u003eJ. Dubowik, K. Załski, I. Gościańska, H. Głowiński, and A. Ehresmann, Appl.\u0026nbsp;Phys. Lett. \u003cstrong\u003e100\u003c/strong\u003e, 162403 (2012)\u003c/li\u003e\n \u003cli\u003eRitu Vishnoi and Davinder Kaur, J. Appl. Phys. \u003cstrong\u003e107\u003c/strong\u003e, 103907 (2010)\u003c/li\u003e\n \u003cli\u003eRitu Vishnoi and Davinder Kaur, Journal of Alloys and Compounds \u003cstrong\u003e509\u003c/strong\u003e 2833 (2011)\u003c/li\u003e\n \u003cli\u003eBarsha Borgohain, P. K. Siwach \u0026amp; Nidhi Singh, K. V. R. Rao and H. K. Singh, Journal of Superconductivity and Novel Magnetism \u003cstrong\u003e32\u003c/strong\u003e 3295 (2019)\u003c/li\u003e\n \u003cli\u003eH. Ahmed, H. C. Kandpal, and P. C. Patel, J. Electronic Mater. \u003cstrong\u003e48\u003c/strong\u003e 7944 (2019).\u003c/li\u003e\n \u003cli\u003eNeil Ashcroft and N. D. Mermin, Solid State Physics, Academic Press, New York (1976).\u003c/li\u003e\n \u003cli\u003eR. Harikrishnan, Jatin Kumar Bidika, B. R. K. Nanda, A. J. Chelvane, S. D. Kaushik, P. D. Babu, and Harish Kumar Narayanan, Phys. Rev. B \u003cstrong\u003e108\u003c/strong\u003e, 094407 (2023).\u003c/li\u003e\n \u003cli\u003eT. Fiji, J. of the Japan Institute of Metals and Materials 34(4):456-459 (2008).\u003c/li\u003e\n \u003cli\u003eW.H. Schreiner, P. Pureur, D.E. Brand\u0026atilde;o, Electrical resistivity of the Pd‐based Heusler alloys, Phys. Status Solidi \u003cstrong\u003e60\u0026nbsp;\u003c/strong\u003eK123\u0026ndash;K126 (1980).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eS. Chakraborty, and A.K. Majumdar, Phys. Rev. B \u003cstrong\u003e53\u003c/strong\u003e 6235 (1996).\u003c/li\u003e\n \u003cli\u003eN. Rivier, and K. Adkins, J. Phys. F Met. Phys. \u003cstrong\u003e5\u003c/strong\u003e 1745 (1975).\u003c/li\u003e\n \u003cli\u003eP. V. Prakash Madduri and S. N. Kaul, Phys. Rev. B \u003cstrong\u003e95\u003c/strong\u003e, 184402 (2017).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4540219/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4540219/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe study investigates the effects of annealing on the structural, morphological, magnetic, and transport properties of Mn-Ni-Sn-based Heusler alloy thin films grown by UHV RF Magnetron sputtering. A commercial target with the nominal composition Mn\u003csub\u003e2\u003c/sub\u003e\u003cbr\u003e\nNi\u003csub\u003e1.6\u003c/sub\u003eSn\u003csub\u003e0.4\u003c/sub\u003e was used, and the films were deposited on (001) oriented SrTiO\u003csub\u003e3\u003cbr\u003e\n\u003c/sub\u003esubstrates. Thin films were deposited at 500 °C, 600 °C, 700 °C, and 800 °C and in situ annealing was done at the respective deposition temperatures for 6 hours. X-ray reflectivity indicated a deposition rate of »4 nm/min. The films exhibited B2 or L2\u003csub\u003e1\u003c/sub\u003e-type structures, or a mixture of both, depending on the annealing temperature. At the highest growth temperature (800 °C), additional diffraction maxima between 40-45° were likely due to Ni\u003csub\u003e3\u003c/sub\u003eSn or Mn\u003csub\u003e3\u003c/sub\u003e\u003cbr\u003e\nSn impurity phases, suggesting thermally activated decomposition. Surface microstructures consisting of dark and bright regions evolved from continuous to discontinuous morphology with the increase of the growth temperature. The bifurcation between zero field-cooled (ZFC) and field-cooled warming (FCW) curves decreased, and the magnetic moment increased with deposition temperatures up to 700 °C. The Curie temperature for all films was above room temperature. Films grown at 500 °C, 600 °C, and 700 °C followed the Bloch law below 143 K. However, the film grown at 800 °C, followed this law between 14 K and 75 K. Films grown up to 700 °C behaved like a local magnetic moment system, which is crucial for spin polarization in Heusler systems. Phase degeneration at 800 °C destroyed the half-metallic behavior. All films showed metallic behavior with different resistivity and temperature dependence. Residual Resistivity Ratio (RRR) values were 1.17, 1.51, and 1.64 for films grown at 500 °C, 600 °C, and 700 °C, respectively. The phase degenerated film showed the steepest decline in resistivity, with an exceptionally high RRR of approximately 956.59.\u003c/p\u003e","manuscriptTitle":"Microstructure, Magnetism and Electrical Transport Properties of Mn-Ni-Sn based Heusler Alloy Thin Films Grown Using RF Magnetron Sputtering: Consequences of Annealing Conditions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-27 19:00:34","doi":"10.21203/rs.3.rs-4540219/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9579f1fc-7d5e-4e62-8c0f-df789605c1cd","owner":[],"postedDate":"June 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-08-23T04:23:51+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-27 19:00:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4540219","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4540219","identity":"rs-4540219","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}