Spin orientation switching in layered perovskite oxyfluoride Pb3Fe2O5F2

Spin orientation switching in layered perovskite oxyfluoride Pb3Fe2O5F2 | 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 Article Spin orientation switching in layered perovskite oxyfluoride Pb 3 Fe 2 O 5 F 2 Kengo Oka, Yusuke Nambu, Masayuki Ochi, Naoaki Hayashi, Yoshihiro Kusano, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-678519/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Control of spin alignment in magnetic materials is crucial for developing switching devices. In molecular magnets, magnetic anisotropy can be rationally controlled by varying their ligands that allow tuning of ligand field splitting energy. However, the inherent weak magnetic interaction between spins or spin-cluster results in spin reorientation (SR) occurring only at low temperatures. Here, we show that layered perovskite oxyfluoride Pb 3 Fe 2 O 5 F 2 exhibits a SR transition at 380 K, with the magnetic moments changing from perpendicular to parallel to the c -axis. It is found that the SR is caused by a ferroelectric-like phase transition, where the magnetic HOMO-LUMO interaction changes upon the structural transition due to the concerted effect of the heteroleptic FeO 5 F coordination and the steric effect of Pb. This finding indicates that the design of spin orientation by local coordination environment, which is common in molecular magnets, can be extended to extended oxides by introducing different anions. Hard Condensed-matter Physics Soft Condensed-matter Physics Magnetics Materials and Devices Inorganic Chemistry magnetic materials spin alignment layered perovskite oxyfluoride Pb3Fe2O5F2 Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Controlling the spin orientation, or magnetic anisotropy, in magnetic materials is an essential issue for applications such as magnetic switching devices. For molecular magnets, magnetic anisotropy arises mainly from spin-orbit interaction, thus the most promising and rational approach is to tailor the crystalline field splitting energy using various ligands around a magnetic metal center, as demonstrated in single molecule magnets (SMMs). 1 – 7 Magnetic anisotropy in molecular magnets is theoretically explained by magnetic exchange interaction and ligand field splitting, as applied to Mn 12 -acetate, [Fe 8 O 2 (OH) 12 (tacn) 6 ] 8 and Mn(II)-[3 x 3] grid 9 . Magnetic anisotropy phase diagrams for [PPh 4 ][ Ln {Pt(SAc) 4 } 2 ] ( Ln = Ho, Er) have been reproduced as a function of temperature, magnetic field, and pressure. 7 Despite the tunability and predictable magnetic anisotropy in SMMs, the switching behavior occurs at low temperatures, thereby limiting their applications. Extended solid-state materials, such as oxides, have an advantage over SMMs in terms of higher operating temperatures, which allows for the operation of magnetic devices at room temperature. Unlike SMMs, magnetic interactions are mediated by magnetic ions on infinite magnetic lattices, and long-range magnetic orders such as ferromagnetic and antiferromagnetic states occur depending on the crystal structure and magnetic interactions. However, the local coordination environments around magnetic ion are mostly homoleptic, and limited changes in coordinates do not allow for extensive tuning of crystal filed observed in SMMs. Although some oxides exhibit spin reorientation (SR) as a function of temperature and pressure, the underlying mechanism is far more complex, compared to molecular magnets. For example, the SR transition observed perovskite-based materials, Ln FeO 3 (Ln: Yb, Sm, Er, Tm, Dy) 10 – 15 and MnNdMnSbO 6 , 16 and Mn 2 (Fe 0.8 Mo 0.2 )MoO 6 17 are attributed to the subtle competition between two magnetic sublattices (e.g., Ln- and Fe-sublattices in LnFeO 3 ). Mixed anion compounds have recently been attracting attention as materials that produce structures and functions not found in oxides 18 . In particular, the heteroleptic coordination around a metal center may allow for the intensive tuning of crystal field splitting, as seen in molecular magnets. In this study, we show that layered perovskite oxyfluoride Pb 3 Fe 2 O 5 F 2 exhibits SR above room temperature through a structural transition similar to a ferroelectric transition. As shown schematically illustrated in Fig. 1 , this phase transition drastically changes the heteroleptic coordination environment around Fe 3+ ion and alters the crystal field splitting. This study demonstrates a new possibility in rationally designing magnetic anisotropy of extended solid materials to explore SR at high temperatures. Results And Discussions Powder sample of Pb 3 Fe 2 O 5 F 2 was prepared using the solid-state reaction by heating a mixture of PbO, PbF 2, and Fe 2 O 3 at 600°C for 12 hours in a vacuum. The X-ray diffraction (XRD) data indicated the formation of a double-layered ( n = 2) Ruddlesden-Popper (RP) perovskite (see Supplementary Fig. 1). While related oxyfluorides, Sr 3 Fe 2 O 6 F 0.87 19 and Sr 3 Fe 2 O 5.44 F 1.56 , 20 adopt an ideal tetragonal RP structure, the synchrotron X-ray diffraction (SXRD) profile at 100 K for Pb 3 Fe 2 O 5 F 2 was assigned by a monoclinic cell ( a = 3.9406(1) Å, b = 3.9416(1) Å, c = 21.4002(2) Å, and γ = 89.816(1) °). The structural distortion in perovskite is rationalized using the tolerance factor t , 21 , but the t value for Pb 3 Fe 2 O 5 F 2 is almost unity ( t = 0.98 ~ 1.00) 21 , suggesting that the lowered symmetry arises from the stereochemical effect of Pb 2+ . The temperature evolution of the SXRD patterns (Fig. 2 a) revealed a structural transition, where the unit cell of the high-temperature (HT) phase is given by 2 a p × 2 b p × c p , relative to the primitive cell ( a p × b p × c p ) in the low-temperature (LT) phase. A two-phase coexistence in a wide temperature range (380–400 K on heating and 400 − 320 K on cooling) indicates a first-order nature of the transition, as supported by the magnetic susceptibility (Fig. 2 c, top). The normalized cell parameters show an anisotropic thermal expansion, with a pronounced c -axis reduction with cooling across the phase boundary (Fig. 2 c, middle). 57 Fe-Mössbauer spectra at 500 K and 78 K (Fig. 2 b) consist of a paramagnetic doublet and a magnetic sextet, with linewidths of 0.38 mm/s and 0.31 mm/s, respectively. The nearly resolution-limited spectra are in sharp contrast with the cubic perovskite oxyfluorides, 22 , 23 where anionic-site disorder causes spectrum broadening. For the RP oxyfluorides, anion-disordered Sr 3 Fe 2 O 5 − x F 2 − y and Sr 2 FeO 3 F have broad peaks, while anion-ordered Sr 2 FeO 3 F has a resolution-limited spectrum. 24 These observations indicate that Pb 3 Fe 2 O 5 F 2 has a single iron site, with a full O/F anion order. A hyperfine field (HF) of 53.5 T and an isomer shift (IS) of 0.51 mm/s at 78 K (Supplementary Table 1) are typical of the high-spin Fe 3+ , in agreement with the composition. A steep increase in the magnetic susceptibility below 490 K (Fig. 2 c, top) indicates a canted antiferromagnetic transition in the HT region (Supplementary Fig. 2). For the LT phase, the extinction reflection conditions (Supplementary Fig. 3) and the single-site occupancy of Fe (Fig. 2 b) uniquely gave P 2 1 / m space group. Since O and F atoms are indistinguishable by X-ray, we performed Rietveld refinement of the SXRD data at 100 K using a Pb 3 Fe 2 “O 7 ” composition (Fig. 3 a, Supplementary Table 2). The bond valence sum (BVS) of “oxygen” using the tabulated parameters 25 gave acceptable values for the equatorial (O1: 2.03, O2: 2.06) and the bridging (O3: 1.88) sites, while the apical (O4) site has a significantly smaller value of 1.17. Thus, we conclude that the O4 site is selectively occupied by the fluorine anion. For the HT phase, the reflection conditions (Fig. 3 b) uniquely gave P 4 2 / nbc , and the BVS calculation using the refined structure ( R WP = 6.57% and R I = 4.89%) again supported the selective occupation of F − at the apical site (Supplementary Table 2). The appearance of the superstructure (2 a p × 2 b p × c p ) in the HT phase appears unusual, but the same behavior has been seen in, e.g., BiFeO 3 , 26 BiCoO 3 , 27 and BiZn 0.5 V 0.5 O 3 28 where a ferroelectric-to-paraelectric transition takes place upon heating or applying pressures. Such behavior in Pb 3 Fe 2 O 5 F 2 can be seen by comparing the FeO 2 plane in the two phases (Fig. 3 ). For the HT phase, the staggered alignment of oxide ions along the b axis looks responsible for the 2 a p × 2 b p × c p supercell. In contrast, the LT phase shows a uniform displacement, thus removing the superstructure while inducing a large electronic polarization along the b axis. Note that the antiparallel stacking of the FeO 2 layers cancels out the total electric polarization. Thus, the structural transition in Pb 3 Fe 2 O 5 F 2 can be considered to originate from the steric effect of 6 s 2 lone pair electrons of Pb 2+ . As typified by the multiferroic BiFeO 3 , the steric effect of Bi 3+ and the magnetic moment of Fe 3+ may lead to interesting phenomena induced by the structural phase transition. Neutron powder diffraction (NPD) pattern at 400 K exhibits magnetic reflections given by a propagation vector of k = (0, 0, 0), corresponding to (1/2, 1/2, 0) p in the reduced cell. The Fe magnetic moment increases with decreasing temperature, giving 3.5(1) m B /Fe at 4 K. Magnetic structure refinement with group-theoretical analysis (see Supplementary Information) revealed the G-type antiferromagnetic order, with magnetic moments being perpendicular to the c axis. This spin orientation is consistent with the Mössbauer results (Supplementary Table 1). Most notably, the relative intensity of the magnetic peaks drastically changes; the intensity ratio of I 112 / I 113 is 0.32 at 400 K, but it is reduced to 1.78 at 4 K (Fig. 4 ). This observation strongly indicates that the magnetic moments at 4 K align parallel and antiparallel to the c axis since magnetic neutron scattering can detect spin components perpendicular to the momentum transfer. Indeed, the group-theoretical analysis confirms the SR by comparing the reliable factor through magnetic structure refinements. Thus, the structural transition drives the spin orientation change from perpendicular to parallel to the c axis. As mentioned earlier, SR has been observed in extended solids, but its origin is rather complicated. SR in bulk a-Fe 2 O 3 , known as Morin transition, has been interpreted as originating from the competition between crystalline-, shape- and surface magnetic anisotropy. 29 For other bulk compounds, it is mostly caused by the coupling between two magnetic sublattices, as found in Ln 2 Fe 14 B, 10 – 15 Ln FeO 3 ( Ln = magnetic lanthanides), 30 – 38 MnNdMnSbO 6 , 16 and Mn 2 (Fe 0.8 Mo 0.2 )MoO 6 , 17 with different magnetic sublattices (e.g., Ln -4 f vs . Fe-3 d in Ln FeO 3 ). In these examples, the magnetic order of each sublattice occurs at different temperatures, and the spin orientation of the sublattice with a higher transition temperature (Fe-3 d ) changes when another sublattice ( Ln -4 f ) is ordered upon cooling, indicating that a subtle competition between different sublattices is at play. Other examples include BaFeO 3 with charge disproportionation of Fe ions, 39 Ba 0.65 Na 0.35 Fe 2 As 2 with competing antiferromagnetic and superconducting phases. 40 – 42 The SRs in all of these materials involve strong correlations of electrons. In contrast to the extended solids shown above, the SR in Pb 3 Fe 2 O 5 F 2 is driven by the ferroelectric like phase transition in the perovskite layers of FeO 5 F octahedra. As seen in Fig. 5 , Fe is located approximately at the center of the four equatorial oxygens in the HT phase, but is substantially off-centered in the LT phase. This significant distortion in the LT phase is expected to stabilize the d x 2− y 2 orbital, one of the antibonding orbitals, due to the drastic decrease in the overlap of the O 2p orbitals. According to Whangbo et al. , 43 magnetic anisotropy in extended solids can be predictable by considering the orbitals responsible for magnetic HOMO-LUMO interactions, i.e., the crystal field splitting of d -orbitals. We employ this model to understand the SR in Pb 3 Fe 2 O 5 F 2 . Given high-spin state of Fe 3+ and the Mott insulating nature, the e g orbital as HOMO, we consider magnetic HOMO-LUMO interaction between e g (HOMO: parallel spins) and t 2g (LUMO: anti-parallel spins) orbitals (Supplementary Fig. 5). From the observed spin orientation, the difference in magnetic HOMO-LUMO states ( L values) for in-plane (⊥ c , HP) and perpendicular (// c , LT) spin orientations should be given by |D L Z | = 0 and |D L Z | = 1, respectively. Since the |D L Z | = 0 interaction at HP is possible only for d x 2− y 2 (HOMO) and d xy (LUMO) orbitals, magnetic HOMO is expected to change from d x 2− y 2 (HT phase) to d 3 z 2 − r 2 (LT phase). To verify this scenario, we performed first-principles calculations using density functional theory. The partial density of states (DOS) of Fe 3+ in Fig. 6 a indicates that the magnetic HOMO changes from the d x 2− y 2 band in the HT phase to a mixed band of d x 2− y 2 and d 3 z 2 − r 2 orbitals in the LT phase. The magnetic LUMO is composed of the t 2g orbitals ( d xy , d yz , d xz ) in both phases. This result is consistent with our scenario because in the HT phase has a larger contribution of the d x 2− y 2 (HOMO) and d xy (LUMO) orbitals, responsible for |D L Z |= 0 as shown in Fig. 6 b. Thus, the change in magnetic HOMO is intuitively understood simply through the local coordination environment around Fe 3+ . The magnetic HOMO in the HT phase can be understood as a strong repulsion of electrons in the d x 2− y 2 orbital from O 2p orbitals and a weak repulsion of the d 3 z 2 − r 2 orbital because one of the apical anions being monovalent (see Fig .1). On the other hand, the LT phase has a stabilized d x 2− y 2 orbital, which increase the contribution of d 3 z 2 − r 2 orbital to magnetic HOMO. In molecular magnets including SMMs, control of magnetic anisotropy by tuning orbital splitting has been achieved using a variety of ligands. 6 However, while the nearly isolated spins (or clusters) simplify the interpretation of spin orientation, the weak magnetic interaction between spins (or spin clusters) inevitably lowers the temperature at which the magnetic anisotropy changes. For example, [Mn 12 O 12 (OAc) 16 (H 2 O) 4 ] 44 shows magnetic hysteresis only below 4 K. For most of SMMs, ferromagnetic like behavior is seen below 20 K. 1 , 45 A hexatert-butyldysprosocenium complex shows magnetic hysteresis around 60 K, which is the highest transition temperature. 46 , 47 In marked contrast, Pb 3 Fe 2 O 5 F has the magnetic transition temperature of 490 K and the structural phase transition (and SR) of 380 K, both far beyond room temperature. Given the ferroelectric-like nature of structural transition, the operating temperature might be widely tuned by, e.g., non-magnetic substitution of Pb. Pb 3 Fe 2 O 5 F is a mixed-anion compound, which, as is the case with SMMs, allows the crystal field to be controlled by different ligands to a degree greater than is possible with oxides. Furthermore, the combination of the steric effects of the heteroleptic coordination and lone pair electrons can induce a dramatic change in the ligand field with temperature. These two factors are considered to be essential for temperature-induced SR, and hence it would be possible to search for other materials that satisfy these requirements. Methods Powder sample of Pb 3 Fe 2 O 5 F 2 was prepared through the solid-state reaction using a stoichiometric mixture of PbO (99.9%, Raremetallic Co.), PbF 2 (99.9%, Raremetallic Co.), and α-Fe 2 O 3 (99.9%, Raremetallic Co.) powders. The pelletised mixture was placed in a Pt crucible, sealed in an evacuated Pyrex tube, and reacted at 873 K for 12 h. Synchrotron X-ray diffraction (SXRD) patterns were collected at the beamline BL02B2 of SPring-8 48 and refined by the Rietveld method using the RIETAN-FP program. 49 The SXRD patterns were collected in transmission geometry using a solid state detector. The sample powders were each sealed in glass capillaries and rotated during measurement. The incident beam was monochromatized to λ = 0.41967 Å. Neutron powder diffraction data were collected on HB-2A POWDER installed at High Flux Isotope Reactor, Oak Ridge National Laboratory, USA, with λ = 1.5366 Å and 2.4068 Å. We collected diffraction patterns between T = 4 K and 600 K in a closed-cycle refrigerator. We employed group theoretical analysis to identify magnetic structures that are allowed by symmetry (see Supplementary Information for details). The cross-sectional microstructure and electron diffraction patterns of the Pb 3 Fe 2 O 5 F 2 sample were observed using transmission electron microscopy (TEM, JEOL JEM-2100F and JEM-2800) with energy-dispersive X-ray spectroscopy (EDS) after thinning by Ar ion milling at room temperature. Simulations of ED patterns were carried out using the multislice simulation software MacTempas. We collected 57 Fe Mössbauer spectra using a 57 Co/Rh source and control absorber α-Fe. Magnetic properties were measured with a superconducting quantum interference device (SQUID) magnetometer (MPMS-XL, Quantum Design) equipped with an oven option for high temperatures. First principles calculations were performed on the basis of the density functional theory. Since we perturbatively interpreted the spin-orbit coupling for understanding the magnetic anisotropy, the energy levels used in our discussion as the non-perturbative states were calculated without including the spin-orbit coupling (see Supplementary Information for details). Declarations Acknowledgements We thank Dr. Stuart Calder of Oak Ridge National Laboratory for his help in the neutron diffraction measurement and Prof. Ko Mibu and Tomoko Onoue of Nagoya Institute of Technology for their help in the 57 Fe Mössbauer spectroscopy. This work was supported by a Grant-in-Aid for Scientific Research on Innovative Area “Mixed Anion (Project, 16K21724, 17H05473, 17H05481, 17H05487, 17H05489, 19H04704, 19H04683, 19H04697, 19H04706, 19K05655)” (JSPS). It was also partially supported by a Grant-in-Aids for Scientific Research (C) (Project JP16K05731). The synchrotron radiation experiments were performed at the BL02B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2018A1227, and 2018B1222). The neutron diffraction experiment was performed on HB-2A at High Flux Isotope Reactor, Oak Ridge National Laboratory, USA (Proposal No. IPTS-18713). The neutron powder diffraction study was performed under the GIMRT Program of the Institute for Materials Research, Tohoku University (Proposal No. 19N0007). The 57 Fe Mössbauer spectroscopy was supported by Nanotechnology Platform Program of MEXT, Grant Number JPMXP09S17NI39. The magnetic measurement using SQUID magnetometer was carried out under the Visiting Researcher's Program of the Institute for Solid State Physics, the University of Tokyo. Author Contributions K. O. and H. K. designed the research. K. O. carried out the samples preparation, SXRD, NPD and magnetic measurements. Y. N. analysed NPD patterns and wrote the NPD part. M. O. and K. K. performed first-principles calculations. N. H. and M. T. carried out 57 Fe Mössbauer spectroscopy and data analysis. Y. K., Y. I. and S. M. carried out ED study. T. A. carried out electronic measurements. N. N. and M. I discussed and interpreted the result. K. O. and H. K. prepared the manuscript as corresponding authors. Competing Interests statement There are no competing interests in the manuscript. References 1 Woodruff, D. N., Winpenny, R. E. P. & Layfield, R. A. Lanthanide Single-Molecule Magnets. Chem. Rev. 113 , 5110-5148, doi:10.1021/cr400018q (2013). 2 Liddle, S. T. & van Slageren, J. Improving f-element single molecule magnets. Chem. Soc. Rev. 44 , 6655-6669, doi:10.1039/C5CS00222B (2015). 3 Craig, G. A. & Murrie, M. 3d single-ion magnets. Chem. Soc. Rev. 44 , 2135-2147, doi:10.1039/C4CS00439F (2015). 4 Cucinotta, G. et al. Magnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural Correlations. Angew. Chem. Int. Ed. 51 , 1606-1610, doi:10.1002/anie.201107453 (2012). 5 Perfetti, M. & Bendix, J. Descriptors of magnetic anisotropy revisited. Chem. Commun. 54 , 12163-12166, doi:10.1039/C8CC05756G (2018). 6 Perfetti, M. et al. Magnetic Anisotropy Switch: Easy Axis to Easy Plane Conversion and Vice Versa. Adv. Funct. Mater. 28 , 1801846, doi:10.1002/adfm.201801846 (2018). 7 Perfetti, M. & Bendix, J. The Multiple Faces, and Phases, of Magnetic Anisotropy. lnorg. Chem. 58 , 11875-11882, doi:10.1021/acs.inorgchem.9b00636 (2019). 8 Postnikov, A. V., Kortus, J. & Pederson, M. R. Density functional studies of molecular magnets. Phys. status solidi 243 , 2533-2572, doi:https://doi.org/10.1002/pssb.200541490 (2006). 9 Waldmann, O., Zhao, L. & Thompson, L. K. Field-Dependent Anisotropy Change in a Supramolecular Mn(II)- [3 ╳ 3] Grid. Phys. Rev. Lett. 88 , 066401, doi:10.1103/PhysRevLett.88.066401 (2002). 10 Burlet, P., Coey, J. M. D., Gavigan, J. P., Givord, D. & Meyer, C. A note on exchange and crystal field interactions in R 2 Fe 14 B compounds: Yb 2 Fe 14 B. Solid State Commun. 60 , 723-727, doi:https://doi.org/10.1016/0038-1098(86)90430-8 (1986). 11 Abache, C. & Oesterreicher, J. Magnetic anisotropies and spin reorientations of R 2 Fe 14 B‐type compounds. J. Appl. Phys. 60 , 3671-3679, doi:10.1063/1.337574 (1986). 12 Yelon, W. B. & Herbst, J. F. Neutron scattering studies of the spin reorientation in Er 2 Fe 14 B. J. Appl. Phys. 59 , 93-96, doi:10.1063/1.336845 (1986). 13 Hirosawa, S. et al. Magnetization and magnetic anisotropy of R 2 Fe 14 B measured on single crystals. J. Appl. Phys. 59 , 873-879, doi:10.1063/1.336611 (1986). 14 Piqué, C., Burriel, R. & Bartolomé, J. Spin reorientation phase transitions in R 2 Fe 14 B ( R = Y, Nd, Ho, Er, Tm) investigated by heat capacity measurements. J. Magn. Magn. Mater. 154 , 71-82, doi:https://doi.org/10.1016/0304-8853(95)00571-4 (1996). 15 García, L. M., Chaboy, J., Bartolomé, F. & Goedkoop, J. B. Orbital Magnetic Moment Instability at the Spin Reorientation Transition of Nd 2 Fe 14 B. Phys. Rev. Lett. 85 , 429-432, doi:10.1103/PhysRevLett.85.429 (2000). 16 Solana-Madruga, E. et al. Double Double Cation Order in the High-Pressure Perovskites Mn R MnSbO 6 . Angew. Chem. Int. Ed. 55 , 9340-9344, doi:10.1002/anie.201603526 (2016). 17 Li, M.-R. et al. Mn 2 (Fe 0.8 Mo 0.2 )MoO 6 : A Double Perovskite with Multiple Transition Metal Sublattice Magnetic Effects. Chem. Mater. 30 , 4508-4514, doi:10.1021/acs.chemmater.8b00250 (2018). 18 Kageyama, H. et al. Expanding frontiers in materials chemistry and physics with multiple anions. Nat. Commun 9 , 772, doi:10.1038/s41467-018-02838-4 (2018). 19 Simon Case, G. et al. Syntheses, powder neutron diffraction structures and Mössbauer studies of some complex iron oxyfluorides: Sr 3 Fe 2 O 6 F 0.87 , Sr 2 FeO 3 F and Ba 2 InFeO 5 F 0.68 . J. Mater. Chem. 9 , 2821-2827, doi:10.1039/A905730G (1999). 20 Tsujimoto, Y. et al. Topotactic Synthesis and Crystal Structure of a Highly Fluorinated Ruddlesden–Popper-Type Iron Oxide, Sr 3 Fe 2 O 5+ x F 2– x ( x ≈ 0.44). Chem. Mater. 23 , 3652-3658, doi:10.1021/cm201075g (2011). 21 Tilley, R. J. D. Perovskites: Structure-Property Relationships. Wiley (2016). 22 Inaguma, Y. et al. Structure and Mossbauer studies of F-O ordering in antiferromagnetic perovskite PbFeO 2 F. Chem. Mater. 17 , 1386-1390, doi:10.1021/cm048125g (2005). 23 Takeiri, F. et al. AgFeOF 2 : A Fluorine-Rich Perovskite Oxyfluoride. Inorg. Chem. 57 , 6686-6691, doi:10.1021/acs.inorgchem.8b00500 (2018). 24 Tsujimoto, Y., Matsushita, Y., Hayashi, N., Yamaura, K. & Uchikoshi, T. Anion Order-to-Disorder Transition in Layered Iron Oxyfluoride Sr 2 FeO 3 F Single Crystals. Cryst. Growth Des. 14 , 4278-4284, doi:10.1021/cg500484e (2014). 25 Brown, I. D. & Altermatt, D. Bond-valence parameters obtained from a systematic analysis of the Inorganic Crystal Structure Database. Acta Crystallogr. B 41 , 244-247, doi:doi:10.1107/S0108768185002063 (1985). 26 Belik, A. A., Yusa, H., Hirao, N., Ohishi, Y. & Takayama-Muromachi, E. Structural Properties of Multiferroic BiFeO 3 under Hydrostatic Pressure. Chem. Mater. 21 , 3400-3405, doi:10.1021/cm901008t (2009). 27 Oka, K. et al. Pressure-Induced Spin-State Transition in BiCoO 3 . J. Am. Chem. Soc. 132 , 9438-9443, doi:10.1021/ja102987d (2010). 28 Yu, R. et al. New PbTiO 3 -Type Giant Tetragonal Compound Bi 2 ZnVO 6 and Its Stability under Pressure. Chem. Mater. 27 , 2012-2017, doi:10.1021/cm504133e (2015). 29 Hill, A. H. et al. Neutron Diffraction Study of Mesoporous and Bulk Hematite, α-Fe 2 O 3 . Chem. Mater. 20 , 4891-4899, doi:10.1021/cm800009s (2008). 30 Pierce, R. D., Wolfe, R. & Uitert, L. G. V. Spin Reorientation in Mixed Samarium‐Dysprosium Orthoferrites. J. Appl. Phys. 40 , 1241-1242, doi:10.1063/1.1657611 (1969). 31 White, R. L. Review of Recent Work on the Magnetic and Spectroscopic Properties of the Rare‐Earth Orthoferrites. J. Appl. Phys. 40 , 1061-1069, doi:10.1063/1.1657530 (1969). 32 Abe, M., Gomi, M., Shōno, K., Mori, Y. & Nomura, S. A Method for Measuring the Direction Angle of a Magnetization with a Vibrating Sample Magnetometer: Application to SmFeO 3 in the Spin Reorientation Region. Jpn. J. Appl. Phys. 16 , 279-282, doi:10.1143/jjap.16.279 (1977). 33 Tsymbal, L. T., Kamenev, V. I., Bazaliy, Y. B., Khara, D. A. & Wigen, P. E. Structural properties of ErFeO 3 in the spin-reorientation region. Phys. Rev. B 72 , 052413, doi:10.1103/PhysRevB.72.052413 (2005). 34 Bazaliy, Y. B., Tsymbal, L. T., Kakazei, G. N., Izotov, A. I. & Wigen, P. E. Spin-reorientation in ErFeO 3 Zero-field transitions, three-dimensional phase diagram, and anisotropy of erbium magnetism. Phys. Rev. B 69 , 104429, doi:10.1103/PhysRevB.69.104429 (2004). 35 Berini, B. et al. High temperature phase transitions and critical exponents of Samarium orthoferrite determined by in situ optical ellipsometry. J. Appl. Phys. 111 , 053923, doi:10.1063/1.3692088 (2012). 36 Kimel, A. V., Kirilyuk, A., Tsvetkov, A., Pisarev, R. V. & Rasing, T. Laser-induced ultrafast spin reorientation in the antiferromagnet TmFeO 3 . Nature 429 , 850-853, doi:10.1038/nature02659 (2004). 37 Saito, K., Sato, A., Bhattacharjee, A. & Sorai, M. High-precision detection of the heat-capacity anomaly due to spin reorientation in TmFeO 3 and HoFeO 3 . Solid State Commun. 120 , 129-132, doi:https://doi.org/10.1016/S0038-1098(01)00359-3 (2001). 38 Saito, K. et al. Heat-capacity anomaly due to spin reorientation and thermodynamic functions of ErFeO 3 and TmFeO 3 . J. Magn. Magn. Mater. 225 , 381-388, doi:https://doi.org/10.1016/S0304-8853(00)01268-3 (2001). 39 Tan, Z. et al. Charge disproportionation and interchange transitions in twelve-layer BaFeO 3 . Phys. Rev. B 102 , 054404, doi:10.1103/PhysRevB.102.054404 (2020). 40 Avci, S. et al. Magnetically driven suppression of nematic order in an iron-based superconductor. Nat. Commun. 5 , 3845, doi:10.1038/ncomms4845 (2014). 41 Waßer, F. et al. Spin reorientation in Ba 0.65 Na 0.35 Fe 2 As 2 studied by single-crystal neutron diffraction. Phys. Rev. B 91 , 060505, doi:10.1103/PhysRevB.91.060505 (2015). 42 Song, Y. et al. Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba 0.67 K 0.33 Fe 2 As 2 . Phys. Rev. B 94 , 214516, doi:10.1103/PhysRevB.94.214516 (2016). 43 Whangbo, M. H., Gordon, E. E., Xiang, H., Koo, H. J. & Lee, C. Prediction of Spin Orientations in Terms of HOMO-LUMO Interactions Using Spin-Orbit Coupling as Perturbation. Acc. Chem. Res. 48 , 3080-3087, doi:10.1021/acs.accounts.5b00408 (2015). 44 Sessoli, R., Gatteschi, D., Caneschi, A. & Novak, M. A. Magnetic bistability in a metal-ion cluster. Nature 365 , 141-143, doi:10.1038/365141a0 (1993). 45 Thorarinsdottir, A. E. & Harris, T. D. Metal–Organic Framework Magnets. Chem. Rev. 120 , 8716-8789, doi:10.1021/acs.chemrev.9b00666 (2020). 46 Goodwin, C. A. P., Ortu, F., Reta, D., Chilton, N. F. & Mills, D. P. Molecular magnetic hysteresis at 60 kelvin in dysprosocenium. Nature 548 , 439-442, doi:10.1038/nature23447 (2017). 47 Goodwin, C. A. P. Blocking like it's hot: a synthetic chemists’ path to high-temperature lanthanide single molecule magnets. Dalton Trans. 49 , 14320-14337, doi:10.1039/D0DT01904F (2020). 48 Kawaguchi, S. et al. High-throughput powder diffraction measurement system consisting of multiple MYTHEN detectors at beamline BL02B2 of SPring-8. Rev. Sci. Instrum. 88 , 085111, doi:10.1063/1.4999454 (2017). 49 Izumi, F. & Momma, K. Three-Dimensional Visualization in Powder Diffraction. Solid State Phenom. 130 , 15-20, doi:10.4028/www.scientific.net/SSP.130.15 (2007). Additional Declarations There is NO Competing Interest. Supplementary Files SI3.pdf SUPPLEMENTARY AND ADDITIONAL INFORMATION Cite Share Download PDF Status: Under Review 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-678519","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":42278431,"identity":"dbe0e921-e4ae-4810-a8f9-e0bbcb232935","order_by":0,"name":"Kengo Oka","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9ElEQVRIiWNgGAWjYBACCQY2BoYPQIYBkHEAiHmgwvi1MM4gWQszD1QLAxgTApLtbYmfbWruyJszsCUeLiizk2FgP/yAwXIHbi3SPMcOS+cce2a4s4HtwOEZ55J5GHjSDBgkz+DWIieR3iCdw3Y4weAAe8Nh3jaQI3OAlrfh1dL82+IfXEs9DwP/G/xapCXSjkkztoG0AB3G23aYh0GCgC2SPcfSLHv7nhluOMyWcJjn3HEeNolnBgfw+UXieJvxjR/f7sgbABmfecqq7fn5kx8+lsQTYlBwgIGBGcoERc1hyQZitCADxo+EtYyCUTAKRsHIAQCgv0xJUDrPAwAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-1800-8575","institution":"Kindai University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Kengo","middleName":"","lastName":"Oka","suffix":""},{"id":42278432,"identity":"e22f8a49-cbd1-41ee-ac1b-5f7445886c17","order_by":1,"name":"Yusuke Nambu","email":"","orcid":"https://orcid.org/0000-0003-1167-7124","institution":"Tohoku University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yusuke","middleName":"","lastName":"Nambu","suffix":""},{"id":42278433,"identity":"d38cc3d9-6593-48dd-bcfe-774e2a020818","order_by":2,"name":"Masayuki Ochi","email":"","orcid":"","institution":"Osaka University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Masayuki","middleName":"","lastName":"Ochi","suffix":""},{"id":42278434,"identity":"c78a868c-8d80-4a02-99f7-04f07899a633","order_by":3,"name":"Naoaki Hayashi","email":"","orcid":"","institution":"Osaka Prefecture University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Naoaki","middleName":"","lastName":"Hayashi","suffix":""},{"id":42278435,"identity":"d577943f-d470-4f5b-86c4-941de7a48528","order_by":4,"name":"Yoshihiro Kusano","email":"","orcid":"https://orcid.org/0000-0003-3646-3413","institution":"Okayama University of Science","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yoshihiro","middleName":"","lastName":"Kusano","suffix":""},{"id":42278436,"identity":"cb460dd0-3d6f-44e8-bb70-4b0e4615649a","order_by":5,"name":"Takuya Aoyama","email":"","orcid":"","institution":"Tohoku University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Takuya","middleName":"","lastName":"Aoyama","suffix":""},{"id":42278437,"identity":"b2a960c7-acdd-49bc-a7d3-596ecedc9267","order_by":6,"name":"Yui Ishii","email":"","orcid":"","institution":"Osaka Prefecture University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yui","middleName":"","lastName":"Ishii","suffix":""},{"id":42278438,"identity":"d39977ca-0337-4890-a719-f66c61b2b15f","order_by":7,"name":"Kazuhiko Kuroki","email":"","orcid":"","institution":"Osaka University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kazuhiko","middleName":"","lastName":"Kuroki","suffix":""},{"id":42278439,"identity":"8748deb3-57c2-4f42-becf-2ee0461331a3","order_by":8,"name":"Shigeo Mori","email":"","orcid":"","institution":"Osaka Prefecture University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shigeo","middleName":"","lastName":"Mori","suffix":""},{"id":42278440,"identity":"1330b8f2-110a-491b-bf10-d739f4d8861c","order_by":9,"name":"Mikio Takano","email":"","orcid":"","institution":"Research Institute for Production Development","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mikio","middleName":"","lastName":"Takano","suffix":""},{"id":42278441,"identity":"a5e029ec-cb4b-4b27-a178-22cc3e966942","order_by":10,"name":"Mitsunobu Iwasaki","email":"","orcid":"","institution":"Kindai University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mitsunobu","middleName":"","lastName":"Iwasaki","suffix":""},{"id":42278442,"identity":"9fc033f3-8e0a-41d5-bdce-82c924c1ef06","order_by":11,"name":"Naoki Noma","email":"","orcid":"","institution":"Kindai University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Naoki","middleName":"","lastName":"Noma","suffix":""},{"id":42278443,"identity":"320d22cc-3519-4f8f-8853-82677b2643af","order_by":12,"name":"Hiroshi Kageyama","email":"","orcid":"https://orcid.org/0000-0002-3911-9864","institution":"Kyoto University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hiroshi","middleName":"","lastName":"Kageyama","suffix":""}],"badges":[],"createdAt":"2021-07-02 15:41:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-678519/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-678519/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":11928224,"identity":"39edfc53-a5e4-4ccb-9e44-c01ca8158518","added_by":"auto","created_at":"2021-07-29 16:39:52","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":32593,"visible":true,"origin":"","legend":"The crystal field energies of 3d orbital in ideal regular and distorted octahedra of FeO5F. While the ideal FeO6 octahedron has the Oh symmetry, the ligand replacement by F– stabilizes d3z2–r2, dxz, and dyz orbitals (left). On the other hand, ferroelectric-like distortion stabilizes t dx2–y2 and dxy orbitals and could induce level crossing. ","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/117eb1a0e80fa904c6764aa4.jpg"},{"id":11928078,"identity":"709efd78-29bf-40e3-920a-90e4bf5adde7","added_by":"auto","created_at":"2021-07-29 16:36:52","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":47346,"visible":true,"origin":"","legend":"Structural and magnetic transitions of Pb3Fe2O5F2 at high temperatures. a, Temperature evolution of synchrotron X-ray diffraction pattern ( = 0.41967 Å) on heating. The blue and red annotations indicate the index of peaks for the LT (aP × aP × cP) and HT (2aP × 2aP × cP) phases, respectively, clearly demonstrating the two-phase coexistence at 380 K. b, Temperature evolution of the 57Fe Mössbauer spectra, all fitted well with a Lorentzian function. c, Temperature dependences of (top) the magnetic susceptibility and hyperfine field (HF), (middle) the nomalized lattice parameters (middle), and (bottom) the fraction of the HT phase.","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/1ad3b84d177ffd429ad9d0a6.jpg"},{"id":11928225,"identity":"fb5eeafa-0ce7-4420-88e2-5d80872fc313","added_by":"auto","created_at":"2021-07-29 16:39:52","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":105185,"visible":true,"origin":"","legend":"Structural refinement of Pb3Fe2O5F2 for the LT and HT phases. Results of Rietveld refinement of the SXRD data and the refined structures at (a) 550 K and (b) 100 K (λ = 0.41967 Å). Red crosses, solid black lines, and solid blue lines represent the observed, calculated, and difference intensities, respectively. Green ticks indicate the Bragg peak positions. Stacking of the perovskite double layer viewed along the c (c) and b (d) axes, for the ideal (left) , HT (middle), and (right) LT phases.","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/346cc00438d5d6a14137c813.jpg"},{"id":11928081,"identity":"b66ab314-1468-49f0-b541-883299b60ab8","added_by":"auto","created_at":"2021-07-29 16:36:52","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":84092,"visible":true,"origin":"","legend":"Spin reorientation in Pb3Fe2O5F2. The magnetic reflections in the NPD patterns and the magnetic structures for the (a, c) LT (4 K with λ = 1.5366 Å) and (b, d) HT (400 K with λ = 2.4068 Å) phases. Profiles are shown with Rietveld refinement assuming G-type antiferromagnetic order with c (red) and //c (blue) spin orientations. The bottom lines in a and b are the difference between observed and calculated intensities for each orientation. The change in the intensity ratio of the magnetic peaks indicates spin reorientation occurs simultaneously with the structural transition.","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/b0edb339228596712ce4c259.jpg"},{"id":11928079,"identity":"fd7292be-5ae4-45be-89c9-81d63bdb1402","added_by":"auto","created_at":"2021-07-29 16:36:52","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":50524,"visible":true,"origin":"","legend":"Stabilized dx2-y2 orbital induced by changes in local coordination around Fe3+ between the LT and HT phases. The annotated figures indicate bond lengths in Å scale. (upper) Refined local structures of the FeO5F octahedron of the LT (100 K) and HT (550 K) phases. The local coordination changes anisotropically by the structural transition. (lower) FeO2 place along the ab plane. The pink shades denote dx2–y2 orbital of Fe3+ and solid lines represent the unit cells. The alignment of O ions changes from (left) zigzag to (right) liner manner along the b axis. ","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/55f8bad403cab57e5016beff.jpg"},{"id":11928084,"identity":"e68c86b4-074a-49f4-bf6d-4e12ef782fee","added_by":"auto","created_at":"2021-07-29 16:36:52","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":73451,"visible":true,"origin":"","legend":"Altered magnetic HOMO-LUMO interaction by the structural transition. (upper) Partial density of states (DOS) of Fe3+ for the HT and LT phase. (lower) Schematic diagram illustrates how SR occurs in Pb3Fe2O5F2. Energy diagrams of 3d orbital in FeIIIO5F octahedra for the LT and HT phases are shown with magnetic HOMO, LUMO, and corresponding |LZ|. The |LZ| = 0 and 1 interactions for 3d5 electronic configuration give c and //c orientations, respectively.","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/847bf1f6a16744f1c566ae59.jpg"},{"id":82169633,"identity":"e352c7cb-fb99-460a-821a-8c66af448703","added_by":"auto","created_at":"2025-05-07 09:44:19","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1117384,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/3bae8c12-4397-4d44-bd4c-ffd395cdd8e4.pdf"},{"id":11928083,"identity":"9ce48395-71bc-4b6b-8b89-32092598e574","added_by":"auto","created_at":"2021-07-29 16:36:52","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":3915229,"visible":true,"origin":"","legend":"SUPPLEMENTARY AND ADDITIONAL INFORMATION","description":"","filename":"SI3.pdf","url":"https://assets-eu.researchsquare.com/files/rs-678519/v1/0fddf886d002af49fa8c3b00.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Spin orientation switching in layered perovskite oxyfluoride Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eControlling the spin orientation, or magnetic anisotropy, in magnetic materials is an essential issue for applications such as magnetic switching devices. For molecular magnets, magnetic anisotropy arises mainly from spin-orbit interaction, thus the most promising and rational approach is to tailor the crystalline field splitting energy using various ligands around a magnetic metal center, as demonstrated in single molecule magnets (SMMs).\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e Magnetic anisotropy in molecular magnets is theoretically explained by magnetic exchange interaction and ligand field splitting, as applied to Mn\u003csub\u003e12\u003c/sub\u003e-acetate, [Fe\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e(OH)\u003csub\u003e12\u003c/sub\u003e(tacn)\u003csub\u003e6\u003c/sub\u003e]\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e and Mn(II)-[3 x 3] grid\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Magnetic anisotropy phase diagrams for [PPh\u003csub\u003e4\u003c/sub\u003e][\u003cem\u003eLn\u003c/em\u003e{Pt(SAc)\u003csub\u003e4\u003c/sub\u003e}\u003csub\u003e2\u003c/sub\u003e] (\u003cem\u003eLn\u003c/em\u003e\u0026thinsp;=\u0026thinsp;Ho, Er) have been reproduced as a function of temperature, magnetic field, and pressure.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e Despite the tunability and predictable magnetic anisotropy in SMMs, the switching behavior occurs at low temperatures, thereby limiting their applications.\u003c/p\u003e\n\u003cp\u003eExtended solid-state materials, such as oxides, have an advantage over SMMs in terms of higher operating temperatures, which allows for the operation of magnetic devices at room temperature. Unlike SMMs, magnetic interactions are mediated by magnetic ions on infinite magnetic lattices, and long-range magnetic orders such as ferromagnetic and antiferromagnetic states occur depending on the crystal structure and magnetic interactions. However, the local coordination environments around magnetic ion are mostly homoleptic, and limited changes in coordinates do not allow for extensive tuning of crystal filed observed in SMMs. Although some oxides exhibit spin reorientation (SR) as a function of temperature and pressure, the underlying mechanism is far more complex, compared to molecular magnets. For example, the SR transition observed perovskite-based materials, \u003cem\u003eLn\u003c/em\u003eFeO\u003csub\u003e3\u003c/sub\u003e (Ln: Yb, Sm, Er, Tm, Dy)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e and MnNdMnSbO\u003csub\u003e6\u003c/sub\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e and Mn\u003csub\u003e2\u003c/sub\u003e(Fe\u003csub\u003e0.8\u003c/sub\u003eMo\u003csub\u003e0.2\u003c/sub\u003e)MoO\u003csub\u003e6\u003c/sub\u003e\u003csup\u003e17\u003c/sup\u003e are attributed to the subtle competition between two magnetic sublattices (e.g., Ln- and Fe-sublattices in LnFeO\u003csub\u003e3\u003c/sub\u003e).\u003c/p\u003e\n\u003cp\u003eMixed anion compounds have recently been attracting attention as materials that produce structures and functions not found in oxides \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. In particular, the heteroleptic coordination around a metal center may allow for the intensive tuning of crystal field splitting, as seen in molecular magnets. In this study, we show that layered perovskite oxyfluoride Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e exhibits SR above room temperature through a structural transition similar to a ferroelectric transition. As shown schematically illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, this phase transition drastically changes the heteroleptic coordination environment around Fe\u003csup\u003e3+\u003c/sup\u003e ion and alters the crystal field splitting. This study demonstrates a new possibility in rationally designing magnetic anisotropy of extended solid materials to explore SR at high temperatures.\u003c/p\u003e"},{"header":"Results And Discussions","content":"\u003cp\u003ePowder sample of Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e was prepared using the solid-state reaction by heating a mixture of PbO, PbF\u003csub\u003e2,\u003c/sub\u003e and Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e at 600\u0026deg;C for 12 hours in a vacuum. The X-ray diffraction (XRD) data indicated the formation of a double-layered (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2) Ruddlesden-Popper (RP) perovskite (see Supplementary Fig.\u0026nbsp;1). While related oxyfluorides, Sr\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e6\u003c/sub\u003eF\u003csub\u003e0.87\u003c/sub\u003e\u003csup\u003e19\u003c/sup\u003e and Sr\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5.44\u003c/sub\u003eF\u003csub\u003e1.56\u003c/sub\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e adopt an ideal tetragonal RP structure, the synchrotron X-ray diffraction (SXRD) profile at 100 K for Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e was assigned by a monoclinic cell (\u003cem\u003ea\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.9406(1) \u0026Aring;, \u003cem\u003eb\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.9416(1) \u0026Aring;, \u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;21.4002(2) \u0026Aring;, and \u003cem\u003e\u0026gamma;\u003c/em\u003e\u0026thinsp;=\u0026thinsp;89.816(1) \u0026deg;). The structural distortion in perovskite is rationalized using the tolerance factor \u003cem\u003et\u003c/em\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, but the \u003cem\u003et\u003c/em\u003e value for Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e is almost unity (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.98\u0026thinsp;~\u0026thinsp;1.00)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, suggesting that the lowered symmetry arises from the stereochemical effect of Pb\u003csup\u003e2+\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe temperature evolution of the SXRD patterns (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea) revealed a structural transition, where the unit cell of the high-temperature (HT) phase is given by 2\u003cem\u003ea\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; 2\u003cem\u003eb\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; \u003cem\u003ec\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e, relative to the primitive cell (\u003cem\u003ea\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; \u003cem\u003eb\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; \u003cem\u003ec\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e) in the low-temperature (LT) phase. A two-phase coexistence in a wide temperature range (380\u0026ndash;400 K on heating and 400\u0026thinsp;\u0026minus;\u0026thinsp;320 K on cooling) indicates a first-order nature of the transition, as supported by the magnetic susceptibility (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, top). The normalized cell parameters show an anisotropic thermal expansion, with a pronounced \u003cem\u003ec\u003c/em\u003e-axis reduction with cooling across the phase boundary (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, middle).\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e57\u003c/sup\u003eFe-M\u0026ouml;ssbauer spectra at 500 K and 78 K (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb) consist of a paramagnetic doublet and a magnetic sextet, with linewidths of 0.38 mm/s and 0.31 mm/s, respectively. The nearly resolution-limited spectra are in sharp contrast with the cubic perovskite oxyfluorides,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e where anionic-site disorder causes spectrum broadening. For the RP oxyfluorides, anion-disordered Sr\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u0026thinsp;\u0026minus;\u0026thinsp;\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003eF\u003csub\u003e2\u0026thinsp;\u0026minus;\u0026thinsp;\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e and Sr\u003csub\u003e2\u003c/sub\u003eFeO\u003csub\u003e3\u003c/sub\u003eF have broad peaks, while anion-ordered Sr\u003csub\u003e2\u003c/sub\u003eFeO\u003csub\u003e3\u003c/sub\u003eF has a resolution-limited spectrum.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e These observations indicate that Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e has a single iron site, with a full O/F anion order. A hyperfine field (HF) of 53.5 T and an isomer shift (IS) of 0.51 mm/s at 78 K (Supplementary Table 1) are typical of the high-spin Fe\u003csup\u003e3+\u003c/sup\u003e, in agreement with the composition. A steep increase in the magnetic susceptibility below 490 K (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, top) indicates a canted antiferromagnetic transition in the HT region (Supplementary Fig.\u0026nbsp;2).\u003c/p\u003e\n\u003cp\u003eFor the LT phase, the extinction reflection conditions (Supplementary Fig. 3) and the single-site occupancy of Fe (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb) uniquely gave \u003cem\u003eP\u003c/em\u003e2\u003csub\u003e1\u003c/sub\u003e/\u003cem\u003em\u003c/em\u003e space group. Since O and F atoms are indistinguishable by X-ray, we performed Rietveld refinement of the SXRD data at 100 K using a Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003e\u0026ldquo;O\u003csub\u003e7\u003c/sub\u003e\u0026rdquo; composition (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea, Supplementary Table\u0026nbsp;2). The bond valence sum (BVS) of \u0026ldquo;oxygen\u0026rdquo; using the tabulated parameters\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e gave acceptable values for the equatorial (O1: 2.03, O2: 2.06) and the bridging (O3: 1.88) sites, while the apical (O4) site has a significantly smaller value of 1.17. Thus, we conclude that the O4 site is selectively occupied by the fluorine anion. For the HT phase, the reflection conditions (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb) uniquely gave \u003cem\u003eP\u003c/em\u003e4\u003csub\u003e2\u003c/sub\u003e/\u003cem\u003enbc\u003c/em\u003e, and the BVS calculation using the refined structure (\u003cem\u003eR\u003c/em\u003e\u003csub\u003eWP\u003c/sub\u003e = 6.57% and \u003cem\u003eR\u003c/em\u003e\u003csub\u003eI\u003c/sub\u003e = 4.89%) again supported the selective occupation of F\u003csup\u003e\u0026minus;\u003c/sup\u003e at the apical site (Supplementary Table 2).\u003c/p\u003e\n\u003cp\u003eThe appearance of the superstructure (2\u003cem\u003ea\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; 2\u003cem\u003eb\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; \u003cem\u003ec\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e) in the HT phase appears unusual, but the same behavior has been seen in, e.g., BiFeO\u003csub\u003e3\u003c/sub\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e BiCoO\u003csub\u003e3\u003c/sub\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e and BiZn\u003csub\u003e0.5\u003c/sub\u003eV\u003csub\u003e0.5\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e28\u003c/sup\u003e where a ferroelectric-to-paraelectric transition takes place upon heating or applying pressures. Such behavior in Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e can be seen by comparing the FeO\u003csub\u003e2\u003c/sub\u003e plane in the two phases (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). For the HT phase, the staggered alignment of oxide ions along the \u003cem\u003eb\u003c/em\u003e axis looks responsible for the 2\u003cem\u003ea\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; 2\u003cem\u003eb\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e \u0026times; \u003cem\u003ec\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e supercell. In contrast, the LT phase shows a uniform displacement, thus removing the superstructure while inducing a large electronic polarization along the \u003cem\u003eb\u003c/em\u003e axis. Note that the antiparallel stacking of the FeO\u003csub\u003e2\u003c/sub\u003e layers cancels out the total electric polarization. Thus, the structural transition in Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e can be considered to originate from the steric effect of 6\u003cem\u003es\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e lone pair electrons of Pb\u003csup\u003e2+\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eAs typified by the multiferroic BiFeO\u003csub\u003e3\u003c/sub\u003e, the steric effect of Bi\u003csup\u003e3+\u003c/sup\u003e and the magnetic moment of Fe\u003csup\u003e3+\u003c/sup\u003e may lead to interesting phenomena induced by the structural phase transition. Neutron powder diffraction (NPD) pattern at 400 K exhibits magnetic reflections given by a propagation vector of \u003cem\u003ek\u003c/em\u003e = (0, 0, 0), corresponding to (1/2, 1/2, 0)\u003csub\u003ep\u003c/sub\u003e in the reduced cell. The Fe magnetic moment increases with decreasing temperature, giving 3.5(1) m\u003csub\u003eB\u003c/sub\u003e/Fe at 4 K. Magnetic structure refinement with group-theoretical analysis (see Supplementary Information) revealed the G-type antiferromagnetic order, with magnetic moments being perpendicular to the \u003cem\u003ec\u003c/em\u003e axis. This spin orientation is consistent with the M\u0026ouml;ssbauer results (Supplementary Table 1). Most notably, the relative intensity of the magnetic peaks drastically changes; the intensity ratio of \u003cem\u003eI\u003c/em\u003e\u003csub\u003e112\u003c/sub\u003e/\u003cem\u003eI\u003c/em\u003e\u003csub\u003e113\u003c/sub\u003e is 0.32 at 400 K, but it is reduced to 1.78 at 4 K (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). This observation strongly indicates that the magnetic moments at 4 K align parallel and antiparallel to the \u003cem\u003ec\u003c/em\u003e axis since magnetic neutron scattering can detect spin components perpendicular to the momentum transfer. Indeed, the group-theoretical analysis confirms the SR by comparing the reliable factor through magnetic structure refinements. Thus, the structural transition drives the spin orientation change from perpendicular to parallel to the \u003cem\u003ec\u003c/em\u003e axis.\u003c/p\u003e\n\u003cp\u003eAs mentioned earlier, SR has been observed in extended solids, but its origin is rather complicated. SR in bulk a-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, known as Morin transition, has been interpreted as originating from the competition between crystalline-, shape- and surface magnetic anisotropy.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e For other bulk compounds, it is mostly caused by the coupling between two magnetic sublattices, as found in \u003cem\u003eLn\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e \u003cem\u003eLn\u003c/em\u003eFeO\u003csub\u003e3\u003c/sub\u003e (\u003cem\u003eLn\u003c/em\u003e\u0026thinsp;=\u0026thinsp;magnetic lanthanides),\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e MnNdMnSbO\u003csub\u003e6\u003c/sub\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e and Mn\u003csub\u003e2\u003c/sub\u003e(Fe\u003csub\u003e0.8\u003c/sub\u003eMo\u003csub\u003e0.2\u003c/sub\u003e)MoO\u003csub\u003e6\u003c/sub\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e with different magnetic sublattices (e.g., \u003cem\u003eLn\u003c/em\u003e-4\u003cem\u003ef vs\u003c/em\u003e. Fe-3\u003cem\u003ed\u003c/em\u003e in \u003cem\u003eLn\u003c/em\u003eFeO\u003csub\u003e3\u003c/sub\u003e). In these examples, the magnetic order of each sublattice occurs at different temperatures, and the spin orientation of the sublattice with a higher transition temperature (Fe-3\u003cem\u003ed\u003c/em\u003e) changes when another sublattice (\u003cem\u003eLn\u003c/em\u003e-4\u003cem\u003ef\u003c/em\u003e) is ordered upon cooling, indicating that a subtle competition between different sublattices is at play. Other examples include BaFeO\u003csub\u003e3\u003c/sub\u003e with charge disproportionation of Fe ions,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e Ba\u003csub\u003e0.65\u003c/sub\u003eNa\u003csub\u003e0.35\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eAs\u003csub\u003e2\u003c/sub\u003e with competing antiferromagnetic and superconducting phases.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e The SRs in all of these materials involve strong correlations of electrons.\u003c/p\u003e\n\u003cp\u003eIn contrast to the extended solids shown above, the SR in Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e is driven by the ferroelectric like phase transition in the perovskite layers of FeO\u003csub\u003e5\u003c/sub\u003eF octahedra. As seen in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, Fe is located approximately at the center of the four equatorial oxygens in the HT phase, but is substantially off-centered in the LT phase. This significant distortion in the LT phase is expected to stabilize the \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e orbital, one of the antibonding orbitals, due to the drastic decrease in the overlap of the O 2p orbitals.\u003c/p\u003e\n\u003cp\u003eAccording to Whangbo \u003cem\u003eet al.\u003c/em\u003e,\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e magnetic anisotropy in extended solids can be predictable by considering the orbitals responsible for magnetic HOMO-LUMO interactions, i.e., the crystal field splitting of \u003cem\u003ed\u003c/em\u003e-orbitals. We employ this model to understand the SR in Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e. Given high-spin state of Fe\u003csup\u003e3+\u003c/sup\u003e and the Mott insulating nature, the \u003cem\u003ee\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e orbital as HOMO, we consider magnetic HOMO-LUMO interaction between \u003cem\u003ee\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e (HOMO: parallel spins) and \u003cem\u003et\u003c/em\u003e\u003csub\u003e2g\u003c/sub\u003e (LUMO: anti-parallel spins) orbitals (Supplementary Fig. 5). From the observed spin orientation, the difference in magnetic HOMO-LUMO states (\u003cem\u003eL\u003c/em\u003e values) for in-plane (\u0026perp;\u003cem\u003ec\u003c/em\u003e, HP) and perpendicular (//\u003cem\u003ec\u003c/em\u003e, LT) spin orientations should be given by |D\u003cem\u003eL\u003c/em\u003e\u003csub\u003eZ\u003c/sub\u003e| = 0 and |D\u003cem\u003eL\u003c/em\u003e\u003csub\u003eZ\u003c/sub\u003e| = 1, respectively. Since the |D\u003cem\u003eL\u003c/em\u003e\u003csub\u003eZ\u003c/sub\u003e| = 0 interaction at HP is possible only for \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e (HOMO) and \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003exy\u003c/em\u003e\u003c/sub\u003e (LUMO) orbitals, magnetic HOMO is expected to change from \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e (HT phase) to \u003cem\u003ed\u003c/em\u003e\u003csub\u003e3\u003cem\u003ez\u003c/em\u003e2\u0026thinsp;\u0026minus;\u0026thinsp;\u003cem\u003er\u003c/em\u003e2\u003c/sub\u003e (LT phase).\u003c/p\u003e\n\u003cp\u003eTo verify this scenario, we performed first-principles calculations using density functional theory. The partial density of states (DOS) of Fe\u003csup\u003e3+\u003c/sup\u003e in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea indicates that the magnetic HOMO changes from the \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e band in the HT phase to a mixed band of \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e and \u003cem\u003ed\u003c/em\u003e\u003csub\u003e3\u003cem\u003ez\u003c/em\u003e2\u0026thinsp;\u0026minus;\u0026thinsp;\u003cem\u003er\u003c/em\u003e2\u003c/sub\u003e orbitals in the LT phase. The magnetic LUMO is composed of the \u003cem\u003et\u003c/em\u003e\u003csub\u003e2g\u003c/sub\u003e orbitals (\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003exy\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eyz\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003exz\u003c/em\u003e\u003c/sub\u003e) in both phases. This result is consistent with our scenario because in the HT phase has a larger contribution of the \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e (HOMO) and \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003exy\u003c/em\u003e\u003c/sub\u003e (LUMO) orbitals, responsible for |D\u003cem\u003eL\u003c/em\u003e\u003csub\u003eZ\u003c/sub\u003e|= 0 as shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb. Thus, the change in magnetic HOMO is intuitively understood simply through the local coordination environment around Fe\u003csup\u003e3+\u003c/sup\u003e. The magnetic HOMO in the HT phase can be understood as a strong repulsion of electrons in the \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e orbital from O 2p orbitals and a weak repulsion of the \u003cem\u003ed\u003c/em\u003e\u003csub\u003e3\u003cem\u003ez\u003c/em\u003e2\u0026thinsp;\u0026minus;\u0026thinsp;\u003cem\u003er\u003c/em\u003e2\u003c/sub\u003e orbital because one of the apical anions being monovalent (see Fig .1). On the other hand, the LT phase has a stabilized \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e2\u0026minus;\u003cem\u003ey\u003c/em\u003e2\u003c/sub\u003e orbital, which increase the contribution of \u003cem\u003ed\u003c/em\u003e\u003csub\u003e3\u003cem\u003ez\u003c/em\u003e2\u0026thinsp;\u0026minus;\u0026thinsp;\u003cem\u003er\u003c/em\u003e2\u003c/sub\u003e orbital to magnetic HOMO.\u003c/p\u003e\n\u003cp\u003eIn molecular magnets including SMMs, control of magnetic anisotropy by tuning orbital splitting has been achieved using a variety of ligands.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e However, while the nearly isolated spins (or clusters) simplify the interpretation of spin orientation, the weak magnetic interaction between spins (or spin clusters) inevitably lowers the temperature at which the magnetic anisotropy changes. For example, [Mn\u003csub\u003e12\u003c/sub\u003eO\u003csub\u003e12\u003c/sub\u003e(OAc)\u003csub\u003e16\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e4\u003c/sub\u003e]\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e shows magnetic hysteresis only below 4 K. For most of SMMs, ferromagnetic like behavior is seen below 20 K.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e A hexatert-butyldysprosocenium complex shows magnetic hysteresis around 60 K, which is the highest transition temperature.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eIn marked contrast, Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF has the magnetic transition temperature of 490 K and the structural phase transition (and SR) of 380 K, both far beyond room temperature. Given the ferroelectric-like nature of structural transition, the operating temperature might be widely tuned by, e.g., non-magnetic substitution of Pb. Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF is a mixed-anion compound, which, as is the case with SMMs, allows the crystal field to be controlled by different ligands to a degree greater than is possible with oxides. Furthermore, the combination of the steric effects of the heteroleptic coordination and lone pair electrons can induce a dramatic change in the ligand field with temperature. These two factors are considered to be essential for temperature-induced SR, and hence it would be possible to search for other materials that satisfy these requirements.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003ePowder sample of Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e was prepared through the solid-state reaction using a stoichiometric mixture of PbO (99.9%, Raremetallic Co.), PbF\u003csub\u003e2\u003c/sub\u003e (99.9%, Raremetallic Co.), and α-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (99.9%, Raremetallic Co.) powders. The pelletised mixture was placed in a Pt crucible, sealed in an evacuated Pyrex tube, and reacted at 873 K for 12 h.\u003c/p\u003e \u003cp\u003eSynchrotron X-ray diffraction (SXRD) patterns were collected at the beamline BL02B2 of SPring-8\u003csup\u003e48\u003c/sup\u003e and refined by the Rietveld method using the RIETAN-FP program.\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e The SXRD patterns were collected in transmission geometry using a solid state detector. The sample powders were each sealed in glass capillaries and rotated during measurement. The incident beam was monochromatized to λ = 0.41967 \u0026Aring;.\u003c/p\u003e \u003cp\u003eNeutron powder diffraction data were collected on HB-2A POWDER installed at High Flux Isotope Reactor, Oak Ridge National Laboratory, USA, with λ\u0026thinsp;=\u0026thinsp;1.5366 \u0026Aring; and 2.4068 \u0026Aring;. We collected diffraction patterns between \u003cem\u003eT\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4 K and 600 K in a closed-cycle refrigerator. We employed group theoretical analysis to identify magnetic structures that are allowed by symmetry (see Supplementary Information for details).\u003c/p\u003e \u003cp\u003eThe cross-sectional microstructure and electron diffraction patterns of the Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e sample were observed using transmission electron microscopy (TEM, JEOL JEM-2100F and JEM-2800) with energy-dispersive X-ray spectroscopy (EDS) after thinning by Ar ion milling at room temperature. Simulations of ED patterns were carried out using the multislice simulation software MacTempas.\u003c/p\u003e \u003cp\u003eWe collected \u003csup\u003e57\u003c/sup\u003eFe M\u0026ouml;ssbauer spectra using a \u003csup\u003e57\u003c/sup\u003eCo/Rh source and control absorber α-Fe. Magnetic properties were measured with a superconducting quantum interference device (SQUID) magnetometer (MPMS-XL, Quantum Design) equipped with an oven option for high temperatures.\u003c/p\u003e \u003cp\u003eFirst principles calculations were performed on the basis of the density functional theory. Since we perturbatively interpreted the spin-orbit coupling for understanding the magnetic anisotropy, the energy levels used in our discussion as the non-perturbative states were calculated without including the spin-orbit coupling (see Supplementary Information for details).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank Dr. Stuart Calder of Oak Ridge National Laboratory for his help in the neutron diffraction measurement and Prof. Ko Mibu and Tomoko Onoue of Nagoya Institute of Technology for their help in the \u003csup\u003e57\u003c/sup\u003eFe Mössbauer spectroscopy. This work was supported by a Grant-in-Aid for Scientific Research on Innovative Area \u0026ldquo;Mixed Anion (Project, 16K21724, 17H05473, 17H05481, 17H05487, 17H05489, 19H04704, \u0026nbsp;19H04683, 19H04697, 19H04706, 19K05655)\u0026rdquo; (JSPS). It was also partially supported by a Grant-in-Aids for Scientific Research (C) (Project JP16K05731). The synchrotron radiation experiments were performed at the BL02B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2018A1227, and 2018B1222). The neutron diffraction experiment was performed on HB-2A at High Flux Isotope Reactor, Oak Ridge National Laboratory, USA (Proposal No. IPTS-18713). The neutron powder diffraction study was performed under the GIMRT Program of the Institute for Materials Research, Tohoku University (Proposal No. 19N0007). The \u003csup\u003e57\u003c/sup\u003eFe Mössbauer spectroscopy was supported by Nanotechnology Platform Program of MEXT, Grant Number JPMXP09S17NI39. The magnetic measurement using SQUID magnetometer was carried out under the Visiting Researcher\u0026apos;s Program of the Institute for Solid State Physics, the University of Tokyo.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eK. O. and H. K. designed the research. K. O. carried out the samples preparation, SXRD, NPD and magnetic measurements. Y. N. analysed NPD patterns and wrote the NPD part. M. O. and K. K. performed first-principles calculations. N. H. and M. T. carried out \u003csup\u003e57\u003c/sup\u003eFe Mössbauer spectroscopy and data analysis. Y. K., Y. I. and S. M. carried out ED study. T. A. carried out electronic measurements. N. N. and M. I discussed and interpreted the result. K. O. and H. K. prepared the manuscript as corresponding authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are no competing interests in the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003e1\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Woodruff, D. N., Winpenny, R. E. P. \u0026amp; Layfield, R. A. Lanthanide Single-Molecule Magnets. \u003cem\u003eChem. Rev.\u003c/em\u003e \u003cstrong\u003e113\u003c/strong\u003e, 5110-5148, doi:10.1021/cr400018q (2013).\u003c/p\u003e\n\u003cp\u003e2\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Liddle, S. T. \u0026amp; van Slageren, J. Improving f-element single molecule magnets. \u003cem\u003eChem. Soc. Rev.\u003c/em\u003e \u003cstrong\u003e44\u003c/strong\u003e, 6655-6669, doi:10.1039/C5CS00222B (2015).\u003c/p\u003e\n\u003cp\u003e3\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Craig, G. A. \u0026amp; Murrie, M. 3d single-ion magnets. \u003cem\u003eChem. Soc. Rev.\u003c/em\u003e \u003cstrong\u003e44\u003c/strong\u003e, 2135-2147, doi:10.1039/C4CS00439F (2015).\u003c/p\u003e\n\u003cp\u003e4\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Cucinotta, G.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Magnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural Correlations. \u003cem\u003eAngew. Chem. Int. Ed.\u003c/em\u003e \u003cstrong\u003e51\u003c/strong\u003e, 1606-1610, doi:10.1002/anie.201107453 (2012).\u003c/p\u003e\n\u003cp\u003e5\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Perfetti, M. \u0026amp; Bendix, J. Descriptors of magnetic anisotropy revisited. \u003cem\u003eChem. Commun.\u003c/em\u003e \u003cstrong\u003e54\u003c/strong\u003e, 12163-12166, doi:10.1039/C8CC05756G (2018).\u003c/p\u003e\n\u003cp\u003e6\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Perfetti, M.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Magnetic Anisotropy Switch: Easy Axis to Easy Plane Conversion and Vice Versa. \u003cem\u003eAdv. Funct. Mater.\u003c/em\u003e \u003cstrong\u003e28\u003c/strong\u003e, 1801846, doi:10.1002/adfm.201801846 (2018).\u003c/p\u003e\n\u003cp\u003e7\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Perfetti, M. \u0026amp; Bendix, J. The Multiple Faces, and Phases, of Magnetic Anisotropy. \u003cem\u003elnorg. Chem.\u003c/em\u003e \u003cstrong\u003e58\u003c/strong\u003e, 11875-11882, doi:10.1021/acs.inorgchem.9b00636 (2019).\u003c/p\u003e\n\u003cp\u003e8\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Postnikov, A. V., Kortus, J. \u0026amp; Pederson, M. R. Density functional studies of molecular magnets. \u003cem\u003ePhys. status solidi\u003c/em\u003e \u003cstrong\u003e243\u003c/strong\u003e, 2533-2572, doi:https://doi.org/10.1002/pssb.200541490 (2006).\u003c/p\u003e\n\u003cp\u003e9\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Waldmann, O., Zhao, L. \u0026amp; Thompson, L. K. Field-Dependent Anisotropy Change in a Supramolecular Mn(II)- [3 ╳ 3] Grid. \u003cem\u003ePhys. Rev. Lett.\u003c/em\u003e \u003cstrong\u003e88\u003c/strong\u003e, 066401, doi:10.1103/PhysRevLett.88.066401 (2002).\u003c/p\u003e\n\u003cp\u003e10\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Burlet, P., Coey, J. M. D., Gavigan, J. P., Givord, D. \u0026amp; Meyer, C. A note on exchange and crystal field interactions in \u003cem\u003eR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB compounds: Yb\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB. \u003cem\u003eSolid State Commun.\u003c/em\u003e \u003cstrong\u003e60\u003c/strong\u003e, 723-727, doi:https://doi.org/10.1016/0038-1098(86)90430-8 (1986).\u003c/p\u003e\n\u003cp\u003e11\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Abache, C. \u0026amp; Oesterreicher, J. Magnetic anisotropies and spin reorientations of \u003cem\u003eR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB‐type compounds. \u003cem\u003eJ. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e60\u003c/strong\u003e, 3671-3679, doi:10.1063/1.337574 (1986).\u003c/p\u003e\n\u003cp\u003e12\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Yelon, W. B. \u0026amp; Herbst, J. F. Neutron scattering studies of the spin reorientation in Er\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB. \u003cem\u003eJ. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e59\u003c/strong\u003e, 93-96, doi:10.1063/1.336845 (1986).\u003c/p\u003e\n\u003cp\u003e13\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Hirosawa, S.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Magnetization and magnetic anisotropy of \u003cem\u003eR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB measured on single crystals. \u003cem\u003eJ. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e59\u003c/strong\u003e, 873-879, doi:10.1063/1.336611 (1986).\u003c/p\u003e\n\u003cp\u003e14\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Piqu\u0026eacute;, C., Burriel, R. \u0026amp; Bartolom\u0026eacute;, J. Spin reorientation phase transitions in \u003cem\u003eR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB (\u003cem\u003eR\u003c/em\u003e = Y, Nd, Ho, Er, Tm) investigated by heat capacity measurements. \u003cem\u003eJ. Magn. Magn. Mater.\u003c/em\u003e \u003cstrong\u003e154\u003c/strong\u003e, 71-82, doi:https://doi.org/10.1016/0304-8853(95)00571-4 (1996).\u003c/p\u003e\n\u003cp\u003e15\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Garc\u0026iacute;a, L. M., Chaboy, J., Bartolom\u0026eacute;, F. \u0026amp; Goedkoop, J. B. Orbital Magnetic Moment Instability at the Spin Reorientation Transition of Nd\u003csub\u003e2\u003c/sub\u003eFe\u003csub\u003e14\u003c/sub\u003eB. \u003cem\u003ePhys. Rev. Lett.\u003c/em\u003e \u003cstrong\u003e85\u003c/strong\u003e, 429-432, doi:10.1103/PhysRevLett.85.429 (2000).\u003c/p\u003e\n\u003cp\u003e16\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Solana-Madruga, E.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Double Double Cation Order in the High-Pressure Perovskites Mn\u003cem\u003eR\u003c/em\u003eMnSbO\u003csub\u003e6\u003c/sub\u003e. \u003cem\u003eAngew. Chem. Int. Ed.\u003c/em\u003e \u003cstrong\u003e55\u003c/strong\u003e, 9340-9344, doi:10.1002/anie.201603526 (2016).\u003c/p\u003e\n\u003cp\u003e17\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Li, M.-R.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Mn\u003csub\u003e2\u003c/sub\u003e(Fe\u003csub\u003e0.8\u003c/sub\u003eMo\u003csub\u003e0.2\u003c/sub\u003e)MoO\u003csub\u003e6\u003c/sub\u003e: A Double Perovskite with Multiple Transition Metal Sublattice Magnetic Effects. \u003cem\u003eChem. Mater.\u003c/em\u003e \u003cstrong\u003e30\u003c/strong\u003e, 4508-4514, doi:10.1021/acs.chemmater.8b00250 (2018).\u003c/p\u003e\n\u003cp\u003e18\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Kageyama, H.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Expanding frontiers in materials chemistry and physics with multiple anions. \u003cem\u003eNat. Commun\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 772, doi:10.1038/s41467-018-02838-4 (2018).\u003c/p\u003e\n\u003cp\u003e19\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Simon Case, G.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Syntheses, powder neutron diffraction structures and M\u0026ouml;ssbauer studies of some complex iron oxyfluorides: Sr\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e6\u003c/sub\u003eF\u003csub\u003e0.87\u003c/sub\u003e, Sr\u003csub\u003e2\u003c/sub\u003eFeO\u003csub\u003e3\u003c/sub\u003eF and Ba\u003csub\u003e2\u003c/sub\u003eInFeO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e0.68\u003c/sub\u003e. \u003cem\u003eJ. Mater. Chem.\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 2821-2827, doi:10.1039/A905730G (1999).\u003c/p\u003e\n\u003cp\u003e20\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Tsujimoto, Y.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Topotactic Synthesis and Crystal Structure of a Highly Fluorinated Ruddlesden\u0026ndash;Popper-Type Iron Oxide, Sr\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5+\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003eF\u003csub\u003e2\u0026ndash;\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e (\u003cem\u003ex\u003c/em\u003e \u0026asymp; 0.44). \u003cem\u003eChem. Mater.\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 3652-3658, doi:10.1021/cm201075g (2011).\u003c/p\u003e\n\u003cp\u003e21\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Tilley, R. J. D. Perovskites: Structure-Property Relationships. \u003cem\u003eWiley\u003c/em\u003e (2016).\u003c/p\u003e\n\u003cp\u003e22\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Inaguma, Y.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Structure and Mossbauer studies of F-O ordering in antiferromagnetic perovskite PbFeO\u003csub\u003e2\u003c/sub\u003eF. \u003cem\u003eChem. Mater.\u003c/em\u003e \u003cstrong\u003e17\u003c/strong\u003e, 1386-1390, doi:10.1021/cm048125g (2005).\u003c/p\u003e\n\u003cp\u003e23\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Takeiri, F.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e AgFeOF\u003csub\u003e2\u003c/sub\u003e: A Fluorine-Rich Perovskite Oxyfluoride. \u003cem\u003eInorg. Chem.\u003c/em\u003e \u003cstrong\u003e57\u003c/strong\u003e, 6686-6691, doi:10.1021/acs.inorgchem.8b00500 (2018).\u003c/p\u003e\n\u003cp\u003e24\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Tsujimoto, Y., Matsushita, Y., Hayashi, N., Yamaura, K. \u0026amp; Uchikoshi, T. Anion Order-to-Disorder Transition in Layered Iron Oxyfluoride Sr\u003csub\u003e2\u003c/sub\u003eFeO\u003csub\u003e3\u003c/sub\u003eF Single Crystals. \u003cem\u003eCryst. Growth Des.\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 4278-4284, doi:10.1021/cg500484e (2014).\u003c/p\u003e\n\u003cp\u003e25\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Brown, I. D. \u0026amp; Altermatt, D. Bond-valence parameters obtained from a systematic analysis of the Inorganic Crystal Structure Database. \u003cem\u003eActa Crystallogr. B\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 244-247, doi:doi:10.1107/S0108768185002063 (1985).\u003c/p\u003e\n\u003cp\u003e26\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Belik, A. A., Yusa, H., Hirao, N., Ohishi, Y. \u0026amp; Takayama-Muromachi, E. Structural Properties of Multiferroic BiFeO\u003csub\u003e3\u003c/sub\u003e under Hydrostatic Pressure. \u003cem\u003eChem. Mater.\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 3400-3405, doi:10.1021/cm901008t (2009).\u003c/p\u003e\n\u003cp\u003e27\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Oka, K.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Pressure-Induced Spin-State Transition in BiCoO\u003csub\u003e3\u003c/sub\u003e. \u003cem\u003eJ. Am. Chem. Soc.\u003c/em\u003e \u003cstrong\u003e132\u003c/strong\u003e, 9438-9443, doi:10.1021/ja102987d (2010).\u003c/p\u003e\n\u003cp\u003e28\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Yu, R.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e New PbTiO\u003csub\u003e3\u003c/sub\u003e-Type Giant Tetragonal Compound Bi\u003csub\u003e2\u003c/sub\u003eZnVO\u003csub\u003e6\u003c/sub\u003e and Its Stability under Pressure. \u003cem\u003eChem. Mater.\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, 2012-2017, doi:10.1021/cm504133e (2015).\u003c/p\u003e\n\u003cp\u003e29\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Hill, A. H.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Neutron Diffraction Study of Mesoporous and Bulk Hematite, \u0026alpha;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. \u003cem\u003eChem. Mater.\u003c/em\u003e \u003cstrong\u003e20\u003c/strong\u003e, 4891-4899, doi:10.1021/cm800009s (2008).\u003c/p\u003e\n\u003cp\u003e30\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Pierce, R. D., Wolfe, R. \u0026amp; Uitert, L. G. V. Spin Reorientation in Mixed Samarium‐Dysprosium Orthoferrites. \u003cem\u003eJ. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 1241-1242, doi:10.1063/1.1657611 (1969).\u003c/p\u003e\n\u003cp\u003e31\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;White, R. L. Review of Recent Work on the Magnetic and Spectroscopic Properties of the Rare‐Earth Orthoferrites. \u003cem\u003eJ. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 1061-1069, doi:10.1063/1.1657530 (1969).\u003c/p\u003e\n\u003cp\u003e32\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Abe, M., Gomi, M., Shōno, K., Mori, Y. \u0026amp; Nomura, S. A Method for Measuring the Direction Angle of a Magnetization with a Vibrating Sample Magnetometer: Application to SmFeO\u003csub\u003e3\u003c/sub\u003e in the Spin Reorientation Region. \u003cem\u003eJpn. J. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e16\u003c/strong\u003e, 279-282, doi:10.1143/jjap.16.279 (1977).\u003c/p\u003e\n\u003cp\u003e33\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Tsymbal, L. T., Kamenev, V. I., Bazaliy, Y. B., Khara, D. A. \u0026amp; Wigen, P. E. Structural properties of ErFeO\u003csub\u003e3\u003c/sub\u003e in the spin-reorientation region. \u003cem\u003ePhys. Rev. B\u003c/em\u003e \u003cstrong\u003e72\u003c/strong\u003e, 052413, doi:10.1103/PhysRevB.72.052413 (2005).\u003c/p\u003e\n\u003cp\u003e34\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Bazaliy, Y. B., Tsymbal, L. T., Kakazei, G. N., Izotov, A. I. \u0026amp; Wigen, P. E. Spin-reorientation in ErFeO\u003csub\u003e3\u003c/sub\u003e Zero-field transitions, three-dimensional phase diagram, and anisotropy of erbium magnetism. \u003cem\u003ePhys. Rev. B\u003c/em\u003e \u003cstrong\u003e69\u003c/strong\u003e, 104429, doi:10.1103/PhysRevB.69.104429 (2004).\u003c/p\u003e\n\u003cp\u003e35\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Berini, B.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e High temperature phase transitions and critical exponents of Samarium orthoferrite determined by in situ optical ellipsometry. \u003cem\u003eJ. Appl. Phys.\u003c/em\u003e \u003cstrong\u003e111\u003c/strong\u003e, 053923, doi:10.1063/1.3692088 (2012).\u003c/p\u003e\n\u003cp\u003e36\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Kimel, A. V., Kirilyuk, A., Tsvetkov, A., Pisarev, R. V. \u0026amp; Rasing, T. Laser-induced ultrafast spin reorientation in the antiferromagnet TmFeO\u003csub\u003e3\u003c/sub\u003e. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e429\u003c/strong\u003e, 850-853, doi:10.1038/nature02659 (2004).\u003c/p\u003e\n\u003cp\u003e37\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Saito, K., Sato, A., Bhattacharjee, A. \u0026amp; Sorai, M. High-precision detection of the heat-capacity anomaly due to spin reorientation in TmFeO\u003csub\u003e3\u003c/sub\u003e and HoFeO\u003csub\u003e3\u003c/sub\u003e. \u003cem\u003eSolid State Commun.\u003c/em\u003e \u003cstrong\u003e120\u003c/strong\u003e, 129-132, doi:https://doi.org/10.1016/S0038-1098(01)00359-3 (2001).\u003c/p\u003e\n\u003cp\u003e38\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Saito, K.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Heat-capacity anomaly due to spin reorientation and thermodynamic functions of ErFeO\u003csub\u003e3\u003c/sub\u003e and TmFeO\u003csub\u003e3\u003c/sub\u003e. \u003cem\u003eJ. Magn. Magn. Mater.\u003c/em\u003e \u003cstrong\u003e225\u003c/strong\u003e, 381-388, doi:https://doi.org/10.1016/S0304-8853(00)01268-3 (2001).\u003c/p\u003e\n\u003cp\u003e39\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Tan, Z.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Charge disproportionation and interchange transitions in twelve-layer BaFeO\u003csub\u003e3\u003c/sub\u003e. \u003cem\u003ePhys. Rev. B\u003c/em\u003e \u003cstrong\u003e102\u003c/strong\u003e, 054404, doi:10.1103/PhysRevB.102.054404 (2020).\u003c/p\u003e\n\u003cp\u003e40\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Avci, S.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Magnetically driven suppression of nematic order in an iron-based superconductor. \u003cem\u003eNat. Commun.\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 3845, doi:10.1038/ncomms4845 (2014).\u003c/p\u003e\n\u003cp\u003e41\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Wa\u0026szlig;er, F.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Spin reorientation in Ba\u003csub\u003e0.65\u003c/sub\u003eNa\u003csub\u003e0.35\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eAs\u003csub\u003e2\u003c/sub\u003e studied by single-crystal neutron diffraction. \u003cem\u003ePhys. Rev. B\u003c/em\u003e \u003cstrong\u003e91\u003c/strong\u003e, 060505, doi:10.1103/PhysRevB.91.060505 (2015).\u003c/p\u003e\n\u003cp\u003e42\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Song, Y.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba\u003csub\u003e0.67\u003c/sub\u003eK\u003csub\u003e0.33\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eAs\u003csub\u003e2\u003c/sub\u003e. \u003cem\u003ePhys. Rev. B\u003c/em\u003e \u003cstrong\u003e94\u003c/strong\u003e, 214516, doi:10.1103/PhysRevB.94.214516 (2016).\u003c/p\u003e\n\u003cp\u003e43\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Whangbo, M. H., Gordon, E. E., Xiang, H., Koo, H. J. \u0026amp; Lee, C. Prediction of Spin Orientations in Terms of HOMO-LUMO Interactions Using Spin-Orbit Coupling as Perturbation. \u003cem\u003eAcc. Chem. Res.\u003c/em\u003e \u003cstrong\u003e48\u003c/strong\u003e, 3080-3087, doi:10.1021/acs.accounts.5b00408 (2015).\u003c/p\u003e\n\u003cp\u003e44\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Sessoli, R., Gatteschi, D., Caneschi, A. \u0026amp; Novak, M. A. Magnetic bistability in a metal-ion cluster. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e365\u003c/strong\u003e, 141-143, doi:10.1038/365141a0 (1993).\u003c/p\u003e\n\u003cp\u003e45\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Thorarinsdottir, A. E. \u0026amp; Harris, T. D. Metal\u0026ndash;Organic Framework Magnets. \u003cem\u003eChem. Rev.\u003c/em\u003e \u003cstrong\u003e120\u003c/strong\u003e, 8716-8789, doi:10.1021/acs.chemrev.9b00666 (2020).\u003c/p\u003e\n\u003cp\u003e46\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Goodwin, C. A. P., Ortu, F., Reta, D., Chilton, N. F. \u0026amp; Mills, D. P. Molecular magnetic hysteresis at 60 kelvin in dysprosocenium. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e548\u003c/strong\u003e, 439-442, doi:10.1038/nature23447 (2017).\u003c/p\u003e\n\u003cp\u003e47\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Goodwin, C. A. P. Blocking like it\u0026apos;s hot: a synthetic chemists\u0026rsquo; path to high-temperature lanthanide single molecule magnets. \u003cem\u003eDalton Trans.\u003c/em\u003e \u003cstrong\u003e49\u003c/strong\u003e, 14320-14337, doi:10.1039/D0DT01904F (2020).\u003c/p\u003e\n\u003cp\u003e48\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Kawaguchi, S.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e High-throughput powder diffraction measurement system consisting of multiple MYTHEN detectors at beamline BL02B2 of SPring-8. \u003cem\u003eRev. Sci. Instrum.\u003c/em\u003e \u003cstrong\u003e88\u003c/strong\u003e, 085111, doi:10.1063/1.4999454 (2017).\u003c/p\u003e\n\u003cp\u003e49\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Izumi, F. \u0026amp; Momma, K. Three-Dimensional Visualization in Powder Diffraction. \u003cem\u003eSolid State Phenom.\u003c/em\u003e \u003cstrong\u003e130\u003c/strong\u003e, 15-20, doi:10.4028/www.scientific.net/SSP.130.15 (2007).\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"magnetic materials, spin alignment, layered perovskite oxyfluoride Pb3Fe2O5F2","lastPublishedDoi":"10.21203/rs.3.rs-678519/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-678519/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eControl of spin alignment in magnetic materials is crucial for developing switching devices. In molecular magnets, magnetic anisotropy can be rationally controlled by varying their ligands that allow tuning of ligand field splitting energy. However, the inherent weak magnetic interaction between spins or spin-cluster results in spin reorientation (SR) occurring only at low temperatures. Here, we show that layered perovskite oxyfluoride Pb\u003csub\u003e3\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003eF\u003csub\u003e2\u003c/sub\u003e exhibits a SR transition at 380 K, with the magnetic moments changing from perpendicular to parallel to the \u003cem\u003ec\u003c/em\u003e-axis. It is found that the SR is caused by a ferroelectric-like phase transition, where the magnetic HOMO-LUMO interaction changes upon the structural transition due to the concerted effect of the heteroleptic FeO\u003csub\u003e5\u003c/sub\u003eF coordination and the steric effect of Pb. This finding indicates that the design of spin orientation by local coordination environment, which is common in molecular magnets, can be extended to extended oxides by introducing different anions.\u003c/p\u003e","manuscriptTitle":"Spin orientation switching in layered perovskite oxyfluoride Pb3Fe2O5F2","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2021-07-29 16:36:50","doi":"10.21203/rs.3.rs-678519/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a503f625-87f4-43b7-bf6d-620de7694150","owner":[],"postedDate":"July 29th, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":6083638,"name":"Hard Condensed-matter Physics"},{"id":6083639,"name":"Soft Condensed-matter Physics"},{"id":6083640,"name":"Magnetics Materials and Devices"},{"id":6083641,"name":"Inorganic Chemistry"}],"tags":[],"updatedAt":"2026-04-13T20:20:58+00:00","versionOfRecord":[],"versionCreatedAt":"2021-07-29 16:36:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-678519","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-678519","identity":"rs-678519","version":["v1"]},"buildId":"-HB7Z8yhvgn0wM9Nzuekk","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}