{"paper_id":"014da2c8-c09e-48ed-af5e-7465e15764b8","body_text":"Superconductivity of the hybrid Ruddlesden‒Popper La5Ni3O11 single crystals under high pressure | 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 Superconductivity of the hybrid Ruddlesden‒Popper La5Ni3O11 single crystals under high pressure Xianhui Chen, Mengzhu Shi, Di Peng, Kaibao Fan, Zhenfang Xing, and 10 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5955283/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 Sep, 2025 Read the published version in Nature Physics → Version 1 posted You are reading this latest preprint version Abstract The discovery of high-temperature superconductivity in La 3 Ni 2 O 7 and La 4 Ni 3 O 10 under high pressure indicates that the Ruddlesden‒Popper ( RP ) phase nickelates R n+1 Ni n O 3n+1 ( R = rare earth) is a new material family for high-temperature superconductivity. Exploring the superconductivity of other RP or hybrid RP phase nickelates under high pressure has become an urgent and interesting issue. Here, we report a novel hybrid RP nickelate superconductor of La 5 Ni 3 O 11 . The hybrid RP nickelate La 5 Ni 3 O 11 is formed by alternative stacking of La 3 Ni 2 O 7 with n=2 and La 2 NiO 4 with n=1 along the c axis. The transport and magnetic torque measurements indicate a density-wave transition at approximately 170 K near ambient pressure, which is highly similar to both La 3 Ni 2 O 7 and La 4 Ni 3 O 10 . With increasing pressure, high-pressure transport measurements reveal that the density-wave transition temperature ( T DW ) continuously increases to approximately 210 K with increasing pressure up to 12 GPa before the appearance of pressure-induced superconductivity, and the density-wave transition abruptly fades out in a first-order manner at approximately 12 GPa. The optimal superconductivity with T c onset = 64 K and T c zero = 54 K is achieved at approximately 21 GPa. On the other hand, high-pressure X-ray diffraction experiments reveal a structural phase transition from an orthorhombic structure to a tetragonal structure at approximately 4.5 GPa. In contrast to La 3 Ni 2 O 7 and La 4 Ni 3 O 10 , the pressure-induced structural transition has no significant effect on either the density-wave transition or the superconductivity, suggesting a minor role of lattice degree of freedom in La 5 Ni 3 O 11 . The present discovery extends the superconducting member in the RP nickelate family and sheds new light on the superconducting mechanism. Physical sciences/Physics/Condensed-matter physics/Superconducting properties and materials Physical sciences/Materials science/Condensed-matter physics/Superconducting properties and materials Figures Figure 1 Figure 2 Figure 3 Figure 4 Full Text Since the discovery of superconductivity in cuprates, exploring high-temperature superconducting materials with similar crystal and electronic structures has become an important research direction 1,2,3,4,5,6,7 . A major breakthrough in this field was made in the infinite-layer nickelate Nd 0.8 Sr 0.2 NiO 2 thin films with a superconducting transition temperature ( T c ) of 9--15 K in 2019 8 . Motivated by this groundbreaking finding, the Ruddlesden‒Popper ( RP ) phase nickelates R n+1 Ni n O 3n+1 ( R = rare earth) with n = 2 and n = 3 are reported to exhibit superconductivity under pressure 9,10,11,12,13 , which largely expands the family of nickelate superconductors. In these RP nickelates R n+1 Ni n O 3n+1 ( R = rare earth), the multilayer perovskite structure ( R NiO 3 ) n is believed to be the fundamental building block for superconductivity. Clarifying the role of the multilayer perovskite structure ( R NiO 3 ) n in the superconducting phase is important for building a theoretical model for the superconducting mechanism. At ambient pressure, the NiO 6 octahedron in the ( R NiO 3 ) n structure is distorted and tilted, which leads to an orthorhombic structure. Moreover, in such an orthorhombic structure phase, a density-wave (DW) transition is widely observed at approximately 130--150 K in RP nickelates with n = 2 and 3, which involves both spin and charge density wave orders 14 , 15 , 16 . With increasing pressure, the distortion and tilting of the NiO 6 octahedron are strongly suppressed, and a pressure-induced structural transition from an orthorhombic structure to a tetragonal structure occurs at approximately 15 GPa 9,12 , 11 . Previous high-pressure transport measurements suggest that the DW transition is also suppressed with increasing pressure, and the pressure-dependent phase diagram of superconductivity and density-wave order suggests a possible competing scenario with a second-order manner 9 , 17 . In addition to RP-phase nickelates, hybrid RP -phase nickelates has been also reported 18 , 19 , 20 . Hybrid RP -phase nickelates are formed by alternative stacking of different RP phases along the c axis. To date, two hybrid RP -phase nickelates have been reported: the 1313 phase, with a chemical formula of La 3 Ni 2 O 7, and the 1212 phase, with a chemical formula of La 5 Ni 3 O 11 18 , 19 , 20 . In the 1313 phase, the (LaNiO 3 ) 3 layer and La 2 NiO 4 layer alternately stack along the c axis and are separated by the LaO layer. Previous high-pressure transport measurements suggest possible high-temperature superconductivity in the 1313 phase, with an onset transition temperature of approximately 80 K 20 . Since there are no reports on superconductivity in the La 2 NiO 4 phase, the superconducting pairing should come from the (LaNiO 3 ) 3 layer. This result further supports the use of the multilayer perovskite structure ( R NiO 3 ) n as the fundamental building block for superconductivity. However, there is a hot debate on the superconducting phase for pressurized superconductors with the chemical formula La 3 Ni 2 O 7 and the onset transition temperature T c onset = 80 K because this chemical formula can share either the RP phase R n+1 Ni n O 3n+1 with n = 2 or the hybrid RP 1313 phase, which is formed by alternative stacking of the (LaNiO 3 ) 3 layer and the La 2 NiO 4 layer along the c axis. Furthermore, T c onset = 80 K in the hybrid RP 1313 phase seems to conflict with the reported superconductivity with a T c onset of less than 30 K in the pressurized RP trilayer nickelate La 4 Ni 3 O 10 10,11,12,13 ; more experiments on the origin of superconductivity in the 1313 phase are needed. Because the multilayer perovskite structure ( R NiO 3 ) n serves as the fundamental building block for superconductivity, high-temperature superconductivity should be expected in the 1212 phase under pressure. In the 1212 phase, as shown in Fig. 1a, the single-layer and bilayer blocks of NiO 6 octahedron alternately stack along the c axis, forming the so-called hybrid RP 1212 nickelate 18 . In this work, we perform a systematic study on the pressure-dependent evolution of the electronic state in a hybrid RP 1212 nickelate single crystal with a chemical formula of La 5 Ni 3 O 11 . High-pressure transport measurements using helium gas as the pressure transmitting medium revealed an unambiguous superconducting transition above ~ 12 GPa. The optimal superconducting transition temperature of a T c onset of ~ 64 K and a zero-resistivity temperature ( T c zero ) of ~ 54 K is achieved at approximately 21 GPa. In addition, the pressure-dependent evolution of the superconductivity, DW transition and structure are also mapped out. Structure and density-wave transition at nearly ambient pressure The hybrid RP 1212 nickelate single crystal was synthesized through a melt‒salt method (see Methods for details). After the flux was dissolved in water, the product was filtered with 400-mesh (~38.5 µm) sieves. A single crystal with typical dimensions of 0.1×0.1×0.02 mm was carefully checked via a four-circle diffractometer. Fig. 1a shows the crystal structure model of the as-grown hybrid RP 1212 nickelate single crystal (left panel) determined from single-crystal X-ray diffraction data, where single-layer and bilayer perovskite-like NiO 6 octahedrons alternately stack along the c -axis direction, as previously reported 18 . The space group is determined to be Cmmm , which is different from the previously reported Immm 18 . We note that the similar compound “1313” phase nickelate, where single-layer and trilayer blocks of NiO 6 octahedrons stack alternately along the c -axis direction, also adopts a Cmmm space group 19 . The structure of the hybrid RP 1212 nickelate is also confirmed by atomically resolved scanning transmission electron microscopy (STEM) images, where the alternate stacking of single-layer and bilayer blocks of NiO 6 octahedrons is clearly observed in Fig. 1b. The overlaid crystal structure model fits well with the STEM-HAADF image (Fig. 1b left panel). By grinding several pieces of hybrid RP 1212 nickelate single crystals, powder X-ray diffraction (XRD) patterns were collected at the Shanghai Synchrotron Radiation Facility at a wavelength of 0.4834 Å at moderate pressure (1.2 GPa) using helium gas as the pressure transmitting medium. With the Rietveld refinement method, the powder XRD pattern can be well fitted with the structural model solved from the single-crystal XRD data. No other RP phase was observed in the powder XRD pattern. In the hybrid RP -phase nickelate La 5 Ni 3 O 11 , the out-of-plane Ni-O-Ni angle between the NiO 6 octahedrons is symmetry constrained to 180° (see Fig. 1a and Table S1), which is different from the value of 168° in La 3 Ni 2 O 7 with the Amam space group at ambient pressure. The out-of-plane Ni-O-Ni angle was previously thought to be critical for interlayer coupling between NiO planes, which favours superconductivity under high pressure. More detailed crystal data, structure refinements and bond angles are shown in Extended Data Table S1 and Extended Data Fig. 1. To obtain good electric contact, the temperature-dependent resistivity curve ( R ( T )) for the as-grown microcrystal was measured on a DAC with a small pressure (~3.5 GPa) (see the inset of Fig. 1d). As shown in Fig. 1d, the resistance curve ( R ( T )) exhibits a large hump at approximately 170 K, which is consistent with a previous report on powder samples at ambient pressure 18 . The anomaly in the resistivity curve is possibly due to a DW transition, which is similar to the other RP phase nickelates and the hybrid RP “1313” phase nickelate 14 , 15 ,19 . Magnetic torque measurements conducted on the hybrid RP 1212 nickelate microcrystal (Fig. 1e) confirmed a DW transition at ~170 K, which corresponds to the temperature at the maximum of the hump in the R ( T ) curve. We note that no obvious nonstoichiometry is observed on the basis of the EDX analysis (Extended Data Fig. 2) and the refinement of the single-crystal XRD data (see Methods). Pressure-induced superconductivity The electrical transport properties of the hybrid RP 1212 nickelate under various pressures were collected on a DAC using helium gas as the pressure transmitting medium 11 . Notably, the homogeneity of the pressure environment is very important for electrical transport measurements under pressure, especially for the hybrid RP 1212 nickelate. Owing to the large volume shrinkage of helium gas under high pressure, good electric contact is quite challenging in practice, and realistic electric contacts usually work well only within a limited pressure range. Here, we successfully measure the electrical transport in different pressure ranges on three pieces of La 5 Ni 3 O 11 single crystals, S2, S3 and S4, which are selected from the same batch. The electric contacts for sample S2 are good only for electrical measurements at relatively low pressures (below ~ 15 GPa), and the electric contacts for samples S3 and S4 are good only for electrical measurements at relatively high pressures (above ~ 15 GPa). For sample S2, the resistance at room temperature gradually decreases at a relatively low pressure (8.9–10.8 GPa, Fig. 2a), and the overall temperature-dependent behavior is similar to that at 3.5 GPa (Fig. 1d). When the applied pressure further increases above 11.7 GPa, although the DW transition temperature remains almost unchanged, the signature of the DW transition in transport is strongly suppressed and completely fades above ~ 13 GPa (Fig. 2b). This result suggests a pressure-induced first-order phase transition for the DW order (Fig. 4a). At ~ 11.7 GPa, a sharp drop in the R ( T ) curve indicates the emergence of superconductivity, with a T c onest of 17.9 K (Fig. 2b). Above 11.7 GPa, the value of T c onest continuously increases and reaches the optimal superconductivity, with the highest T c onest value of ~ 64 K occurring at ~ 21.5 GPa (Figs. 2c and 2d, sample S3). As shown in Fig. 2d, there is a step-like transition at approximately 50 K due to possible inhomogeneity of the pressure environment, which leads to a zero-resistance temperature of only 42 K in sample S3 (Extended Data Fig. 4a). By improving the homogeneity of the pressure environment, we finally obtain a T c onest of ~ 64 K and a T c zero of ~ 54 K for sample S4 (Fig. 2e), which are among the highest reported zero-resistance temperatures and the sharpest superconducting transitions for nickelate superconductors. As shown in Fig. 2e and Extended Data Fig. 4, we studied the superconducting transition under different magnetic fields perpendicular to the ab planes. The upper critical field ( H c2 ) is extracted with different criteria. As shown in Fig. 2f, there is a positive curvature in the H c2 - T c curve, which cannot be explained by a single-band Ginzburg–Landau (GL) model. Here, we use a two-band model at the clean limit to fit the upper critical field, which works quite well and yields H c2 values of 20--28 T at the zero-temperature limit 21 . In La 3 Ni 2 O 7 with the Amam space group, the upper critical field along the out-of-plane direction is ~180 T at 18.9 GPa 9 , which is much greater than that in our case. This low upper critical field in the hybrid RP 1212 nickelate is also confirmed in another single-crystal sample (Extended data Fig. 4b). Above 20 GPa, the superconducting transition temperature starts to slightly decrease with increasing pressure up to 25.2 GPa. Structural transition under pressure To further understand the electrical transport behavior under pressure, we measured the powder XRD patterns under various pressures up to 30.5 GPa for the hybrid 1212 nickelate by grinding several pieces of microcrystals with helium gas as the pressure transmitting medium at the Shanghai Synchrotron Radiation Facility at a wavelength of 0.4834 Å. Fig. 3 and Extended Data Fig. 5 summarize the main results. At ambient pressure, the 1212 nickelate microcrystal adopts an orthorhombic structure with a space group of Cmmm , which is characterized by the splitting of the (020) and (200) diffraction peaks. With increasing pressure, the diffraction peaks of (020) and (200) gradually merged, which indicates a structural transition from the orthorhombic phase to the tetragonal phase below 5.8 GPa (Fig. 3b). In the crystals of La 3 Ni 2 O 7 with the Amam space group and La 4 Ni 3 O 10 , the pressure at which the structure transitions into the tetragonal phase is approximately 14 GPa, which is much greater than that of the hybrid RP 1212 nickelate 9,12 . The refinement of the powder XRD pattern at 5.8 GPa gives a tetragonal phase structure with a space group of P4/mmm (Extended data Fig. 5b), which is similar to the case of the hybrid RP 1313 phase under high pressure 20 . The tetragonal phase structure is maintained at 30.5 GPa. More detailed evolution of the lattice parameters and cell volume are refined and shown in Figs. 3c-d, where the lattice parameters show a progressive decrease under pressure. A careful analysis of the evolution of the lattice parameters of the a- and b -axes indicates that the critical pressure for the structural transition is approximately 4.5 GPa (Fig. 3c). Pressure-dependent phase diagram In Fig. 4a, we summarize the results of high-pressure transport and XRD diffraction into a pressure-dependent phase diagram. As the pressure increases, the crystalline structure of the hybrid RP 1212 nickelate transitions from a low-pressure orthorhombic phase ( Cmmm ) to a high-pressure tetragonal phase ( P4/mmm ) at a critical pressure of ~ 4.5 GPa, which is much lower than that of La 3 Ni 2 O 7 and La 4 Ni 3 O 10 (~ 14 GPa) 9,11 . In contrast to previous high-pressure transport measurements on La 3 Ni 2 O 7 and La 4 Ni 3 O 10 , the density-wave transition in 1212 nickelate is quite robust during the structural transition and is continuously enhanced with increasing pressure. Notably, previous muon spin rotation (μSR) and nuclear magnetic resonance (NMR) experiments on pressurized La 3 Ni 2 O 7 revealed a pressure-enhanced spin-density-wave (SDW) transition 14 ,15 . We speculate that the DW transition in the hybrid RP 1212 nickelate is also related to a similar SDW transition, which needs further experimental investigation in the future. Above 11.7 GPa, the superconducting phase emerges with dome-like pressure-dependent behavior. Our present results indicate strong competition between possible SDW order and superconductivity. They are connected via a first-order phase transition in the pressure-dependent phase diagram. Finally, we also studied the relationship between T c and the average in-plane lattice () in the hybrid RP 1212 nickelate. As shown in Fig. 4b, the relationship between the T c and the average in-plane lattice parameter in 1212 nickelate is similar to that in pressurized La 3 Ni 2 O 7 9, 22 , in which pressure-induced superconductivity appears in the structure with a relatively small (< 3.77 Å). This result suggests that the multilayer perovskite structure ( R NiO 3 ) 3 is the fundamental building block for superconductivity. Very recently, by utilizing compressed strain through a substrate, ambient-pressure superconductivity has been observed in La 3-x Pr x Ni 2 O 7 films 23 , 24 . The relationship between T c and the average in-plane lattice in these La 3-x Pr x Ni 2 O 7 films also shows a similar behavior as that of the bulk samples under pressure. Here, the observation of pressure-induced superconductivity in the hybrid RP 1212 nickelate suggests an alternative route to achieve ambient-pressure superconductivity in the hybrid RP nickelates. The average in-plane lattice parameter of La 2 NiO 4 is approximately 3.85–3.87 Å, which is relatively larger than the average in-plane lattice parameter of La 3 Ni 2 O 7 ( a p =3.835 Å) 25 . If we can replace the La 2 NiO 4 layer with another RP layer with a smaller a p , it might be possible to tune the value of a p to the superconducting region, as shown in Fig. 4b. This deserves further experimental exploration of new hybrid RP nickelates. In summary, by performing high-pressure transport measurements with helium gas as the pressure transmitting medium, we discovered pressure-induced superconductivity with an optimal T c onest of ~ 64 K in a hybrid RP 1212 nickelate single crystal with the chemical formula La 5 Ni 3 O 11 . In contrast to previously reported pressure-induced superconductivity in La 3 Ni 2 O 7 and La 4 Ni 3 O 10 , the ambient-pressure DW order in the hybrid RP 1212 nickelate is quite robust against pressure, and the pressure-dependent phase diagram demonstrates a first-order phase transition between the low-pressure DW order and the high-pressure superconductivity. In addition, a structural transition from the orthorhombic phase to the tetragonal phase is also revealed at 4.5 GPa. Finally, this work also suggests the potential for realizing ambient-pressure superconductivity via sophisticated structural design of hybrid RP nickelates. Declarations Data availability The data that support the findings of this study are available from the corresponding author upon request. Code availability The codes that support the findings of this study are available from the corresponding author upon request. Acknowledgements We acknowledge fruitful discussions with Ho-kwang Mao, Zhengyu Wang and Ziji Xiang. We also thank Zhongliang Zhu, Fujun Lan, Yuxin Liu, and Hongbo Lou for their experimental assistance. This work is supported by the National Natural Science Foundation of China (Grant Nos. 12494592, 12488201, 11888101, 12034004, 12161160316, 12325403, and 12204448), the National Key R&D Program of the MOST of China (Grant No. 2022YFA1602601), the Chinese Academy of Sciences under contract No. JZHKYPT-2021-08, the CAS Project for Young Scientists in Basic Research (Grant No. YBR-048), and the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800). D.P. and Q.Z. acknowledge the financial support from the Shanghai Science and Technology Committee (Grant No. 22JC1410300) and Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (Grant No.22dz2260800). A portion of this research used resources at the beamline 17UM of the Shanghai synchrotron radiation facility. Author contributions X.H.C. conceived the research project and coordinated the experiments. M.Z.S. grew the single crystals and performed the structural characterization at ambient pressure with the help of R.Q.W. and M.D.; H.P.L. and K.B.F. measured the magnetic torque data; S.H.Y. and B.H.G. collected the TEM images; D.P. performed the resistance measurements using helium gas as the pressure-transmitting medium under pressure with the help of Q.S.Z.; D.P., Z.F.X. and Y.Z.W. performed the synchrotron powder diffraction measurements and analysis under high pressure using helium gas as the pressure-transmitting medium with help from Q.S.Z. and Z.D.Z.; M.Z.S., D.P., J.J.Y., T.W. and X.H.C. analysed the data; M.Z.S., D.P., K.B.F., T.W. and X.H.C. wrote the paper with inputs from all the authors. References Bednorz, J. G. & Müller, K. A. Possible high T c superconductivity in the Ba−La−Cu−O system. Z. Phys. B Condens. Matter 64 , 189–193 (1986). Norman, M. R. Materials design for new superconductors. Rep. Prog. Phys. 79 , 074502 (2016). Azuma, M., Hiroi, Z., Takano, M., Bando, Y. & Takeda, Y. Superconductivity at 110 K in the infinite-layer compound (Sr 1-x Ca x ) 1-y CuO 2 . Nature 356 , 775-776 (1992). Anisimov, V. I., Bukhvalov, D. & Rice, T. M. Electronic structure of possible nickelate analogs to the cuprates. Phys. Rev. B 59 , 7901–7906 (1999) Lee, K.-W. & Pickett, W. E. Infinite-layer LaNiO 2 : Ni 1+ is not Cu 2+ . Phys. Rev. B 70 , 165109 (2004). Crespin, M., Levitz, P. & Gatineau, L. Reduced forms of LaNiO 3 perovskite. Part 1.—Evidence for new phases: La 2 Ni 2 O 5 and LaNiO 2 . J. Chem. Soc., Faraday Trans. 2 79 , 1181–1194 (1983). Hayward, M. A., Green, M. A., Rosseinsky, M. J. & Sloan, J. Sodium Hydride as a Powerful Reducing Agent for Topotactic Oxide Deintercalation: Synthesis and Characterization of the Nickel(I) Oxide LaNiO 2 . J. Am. Chem. Soc. 121 , 8843–8854 (1999). Li, D. et al. Superconductivity in an infinite-layer nickelate. Nature 572 , 624–627 (2019). Sun, H. et al. Signatures of superconductivity near 80 K in a nickelate under high pressure. Nature 621 , 493–498 (2023). Li, Q. et al. Signature of Superconductivity in Pressurized La 4 Ni 3 O 10 . Chin. Phys. Lett. 41 , 017401 (2024). Zhu, Y. et al. Superconductivity in tri-layer nickelate La 4 Ni 3 O 10 single crystals. Nature 631 , 531–536 (2024). Zhang, M. et al. Superconductivity in tri-layer nickelate La 4 Ni 3 O 10 under pressure. Preprint at https://doi.org/10.48550/arXiv.2311.07423 (2024). Sakakibara, H. et al. Theoretical analysis on the possibility of superconductivity in the tri-layer Ruddlesden‒Popper nickelate La 4 Ni 3 O 10 under pressure and its experimental examination: Comparison with La 3 Ni 2 O 7 . Phys. Rev. B 109 , 144511 (2024). Dan Z. et al. Spin-density-wave transition in double-layer nickelate La3Ni2O7. Preprint at https://doi.org/10.48550/arXiv.2402.03952 (2024). Chen, K. et al. Evidence of Spin Density Waves in La 3 Ni 2 O 7 − 𝛿 . Phys. Rev. Lett. 132 , 256503 (2024). Zhang, J. et al. Intertwined density waves in a metallic nickelate. Nat. Commun. 11 ,6003 (2020). Zhang, Y. et al. High-temperature superconductivity with zero resistance and strange-metal behavior in La 3 Ni ­2 O 7-δ . Nat. Phys. 20, 1269-1273 (2024). Li F. et al. Design and synthesis of three-dimensional hybrid Ruddlesden‒Popper nickelate single crystals. Phys. Rev. Mater , 8 , 053401 (2024). Chen, X. et al. Polymorphism in the Ruddlesden–Popper Nickelate La 3 Ni 2 O 7 : Discovery of a Hidden Phase with Distinctive Layer Stacking. J. Am. Chem. Soc. 146 , 3640-3645 (2024). Puphal, P. et al. Unconventional Crystal Structure of the High-Pressure Superconductor La 3 Ni 2 O 7 . Phys. Rev. Lett. 133 , 146002 (2024). S. V. Shulga, S.-L. Drechsler, G. Fuchs, K.-H. Müller, K. Winzer, M. Heinecke, and K. Krug, Upper critical field peculiarities of superconducting YNi 2 B 2 C and LuNi 2 B 2 C, Phys. Rev. Lett. 80 , 1730 (1998). Li, J. et al. Pressure-driven right-triangle shape superconductivity in bilayer nickelate La 3 Ni 2 O 7 . Preprint at https://doi.org/10.48550/arXiv.2404.11369 (2024). Liu. Y, et al. Superconductivity and normal-state transport in compressively strained La 2 PrNi 2 O 7 thin films. Preprint at https://doi.org/10.48550/arXiv.2501.08022 (2025). Zhou, G. et al. Ambient-pressure superconductivity onset above 40 K in bilayer nickelate ultrathin films. Preprint at https://doi.org/10.48550/arXiv.2412.16622 (2024). Thanh, TD. et al. Structure, Magnetic, and Electrical Properties of La 2 NiO 4+δ Compounds. IEEE Trans. Magn. 53 , 1-4 (2017). Methods Sample growth: The La 5 Ni 3 O 11 crystals were grown via a melt salt method. First, the La 5 Ni 3 O x precursor (P) was obtained via a standard sol‒gel process. Specifically, the La source (lanthanum nitrate hexahydrate), Ni source (nickel (II) nitrate hexahydrate) and complexing agent (citric acid, CA) were dissolved in water at a molar ratio of La:Ni:CA= 5:3:8. The above solution was preheated at 140 °C for approximately 24 h to obtain a dry gel, which was then transferred into a muffle furnace where the temperature was slowly increased to 400 °C and maintained for another 10 h. Second, the above precursor (P) was mixed with a salt flux (NaCl/KCl mixture) at a mass ratio of P:NaCl:KCl = 1:14:16 and loaded into a corundum crucible. The corundum crucible was heated to 1150 °C for 10 h, maintained at this temperature for 48 h, and then slowly cooled to 1110 °C within 7 days. Microcrystals with a typical size of 0.1×0.1×0.02 mm were obtained after the flux was washed with water. Structural and composition characterization at ambient pressure: The as-grown microcrystal was mounted on the sample holder using high-vacuum silicon grease as the glue. Single-crystal X-ray diffraction (SC-XRD) data were collected on a four-circle diffractometer (Rigaku, XtaLAB PRO 007HF) with Cu Kα radiation at the Core Facility Center for Life Sciences, USTC. The structure was solved and refined via Olex-2 with the ShelXT and ShelXL packages. The detailed structural data are shown in Table S1. All the crystals were first checked via a four-circle diffractometer before they were used to conduct further physical measurements. Energy-dispersive X-ray spectroscopy (EDX) equipped with a scanning electron microscope (SEM, Hitachi SU8220) was used to characterize the chemical composition. The element ratio of La:Ni is approximately 1.67:1 (Extended Data Fig. 2). The refinement of the occupancy of the oxygen sites on the basis of the SC-XRD data gives a value of 0.984--1.072, which indicates nearly full occupation of all these oxygen sites. There is only one oxygen site (O3 site, see Fig. 1a) that is smaller than 1. These results indicate negligible nonstoichiometry in the as-grown La 5 Ni 3 O 11 single crystal. The scanning transmission electron microscopy (STEM) images were collected on a Thermo Fischer Scientific Titan Themis Z microscope with a working voltage of 300 kV. Magnetic torque measurement: Using an SCL piezoresistive cantilever, torque magnetometry data were collected via a physical property measurement system (PPMS, Quantum Design Inc., DynaCool-14T). The sample was carefully attached to the tip of the cantilever, which was fixed on a horizontal rotator. The sample was rotated in the range of q (the angle between the magnetic field vector H (14T)and the flat plane of the La 5 Ni 3 O 11 crystal) from 0° to 90° under isothermal conditions. Electrical transport and XRD measurements under high pressure: Resistance curves for the La 5 Ni 3 O 11 single crystalsunderhigh pressure were measured in a diamond anvil cell (DAC) using helium gas as the pressure transmitting medium. The pressure was applied, and the mixture was calibrated by shifting the ruby florescence at room temperature. The transport measurements were conducted in a Physical Properties Measurement System (PPMS-9, Quantum Design Inc.). The powder XRD data of La 5 Ni 3 O 11 under pressure were collected by gridding several pieces of microcrystals at the Shanghai Synchrotron Radiation Facility via an X-ray beam with a wavelength of 0.4834 Å. Helium gas was used as the pressure transmitting medium. The powder XRD data were refined via GSAS software to obtain the lattice parameters under different pressures. Additional Declarations There is NO Competing Interest. Supplementary Files ExtendedFiguresandTables.docx Cite Share Download PDF Status: Published Journal Publication published 05 Sep, 2025 Read the published version in Nature Physics → 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. 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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-5955283\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":424031135,\"identity\":\"a7a682a4-fe2a-49c9-ab41-7e294b95dd19\",\"order_by\":0,\"name\":\"Xianhui Chen\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAw0lEQVRIiWNgGAWjYDACCSBmbLCB8tiI15IGVU2ClsMkaOGf3XzsMe+O84nz5zc/YPhQdhgo0kDAkjvH0g1nnrmduOEYmwHjjHOHgSIH8GsxkMgxk/jYBtTCxsPAzNt2GCiSQEhL/jeJxLZzifPbgFr+Eqclhw1oy4HEhmNALYzEaJG4kWYmObMt2XjDsTSDgz3n0nkkbhDQwj8j+Zk0b5ud7Pzmww8f/CizluOfQUALCjgAxDwkqB8Fo2AUjIJRgAsAAHQkQS6nns0yAAAAAElFTkSuQmCC\",\"orcid\":\"https://orcid.org/0000-0001-6947-1407\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Xianhui\",\"middleName\":\"\",\"lastName\":\"Chen\",\"suffix\":\"\"},{\"id\":424031136,\"identity\":\"2c1bc2b0-d624-4340-9e7a-cc65c0e0fadc\",\"order_by\":1,\"name\":\"Mengzhu Shi\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Mengzhu\",\"middleName\":\"\",\"lastName\":\"Shi\",\"suffix\":\"\"},{\"id\":424031137,\"identity\":\"9ca60998-edb1-4ece-aee3-9a7ef8e228a8\",\"order_by\":2,\"name\":\"Di Peng\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0002-4235-6385\",\"institution\":\"Institute for Shanghai Advanced Research in Physical Sciences\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Di\",\"middleName\":\"\",\"lastName\":\"Peng\",\"suffix\":\"\"},{\"id\":424031138,\"identity\":\"ad0e7d45-9749-4341-a322-139aca14955d\",\"order_by\":3,\"name\":\"Kaibao Fan\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Kaibao\",\"middleName\":\"\",\"lastName\":\"Fan\",\"suffix\":\"\"},{\"id\":424031139,\"identity\":\"fe6bec1a-932e-4a1a-8178-c9d6015758b2\",\"order_by\":4,\"name\":\"Zhenfang Xing\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Center for High Pressure Science and Technology Advanced Research\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Zhenfang\",\"middleName\":\"\",\"lastName\":\"Xing\",\"suffix\":\"\"},{\"id\":424031140,\"identity\":\"9a7d7f38-670a-4dc4-9686-c955c977bb85\",\"order_by\":5,\"name\":\"Shaohua Yang\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Anhui University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Shaohua\",\"middleName\":\"\",\"lastName\":\"Yang\",\"suffix\":\"\"},{\"id\":424031141,\"identity\":\"1297ff41-e0ac-46bf-b9c8-959c929f2c45\",\"order_by\":6,\"name\":\"Yuzhu Wang\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Yuzhu\",\"middleName\":\"\",\"lastName\":\"Wang\",\"suffix\":\"\"},{\"id\":424031142,\"identity\":\"7f5b333b-ed39-4fdf-99bd-9934479d6fb0\",\"order_by\":7,\"name\":\"Houpu Li\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Houpu\",\"middleName\":\"\",\"lastName\":\"Li\",\"suffix\":\"\"},{\"id\":424031143,\"identity\":\"2ea63c43-c90b-4c93-b50f-f1b59f1f4f29\",\"order_by\":8,\"name\":\"Rongqi Wu\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Rongqi\",\"middleName\":\"\",\"lastName\":\"Wu\",\"suffix\":\"\"},{\"id\":424031144,\"identity\":\"5bdce26d-faa0-4004-a689-8d57d7299ed3\",\"order_by\":9,\"name\":\"Mei Du\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Mei\",\"middleName\":\"\",\"lastName\":\"Du\",\"suffix\":\"\"},{\"id\":424031145,\"identity\":\"cddba877-16f0-40be-be53-eba2628d5b1f\",\"order_by\":10,\"name\":\"Binghui Ge\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0002-6470-6278\",\"institution\":\"Anhui University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Binghui\",\"middleName\":\"\",\"lastName\":\"Ge\",\"suffix\":\"\"},{\"id\":424031146,\"identity\":\"ef8f6aad-edb5-4622-b47f-bb11c7dc2c5f\",\"order_by\":11,\"name\":\"Zhidan Zeng\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0003-4283-2393\",\"institution\":\"Center for High Pressure Science and Technology Advanced Research\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Zhidan\",\"middleName\":\"\",\"lastName\":\"Zeng\",\"suffix\":\"\"},{\"id\":424031147,\"identity\":\"2fc9542b-d948-401e-810d-269376ae4279\",\"order_by\":12,\"name\":\"Qiaoshi Zeng\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0001-5960-1378\",\"institution\":\"Center for High Pressure Science \\u0026 Technology Advanced Research\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Qiaoshi\",\"middleName\":\"\",\"lastName\":\"Zeng\",\"suffix\":\"\"},{\"id\":424031148,\"identity\":\"757c57d3-144a-4409-9df1-cd7b25e8c382\",\"order_by\":13,\"name\":\"Jianjun Ying\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0002-0104-9098\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Jianjun\",\"middleName\":\"\",\"lastName\":\"Ying\",\"suffix\":\"\"},{\"id\":424031149,\"identity\":\"057f2d4e-03f4-4e47-8a45-4a75495bc7bd\",\"order_by\":14,\"name\":\"Tao Wu\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0001-9805-4434\",\"institution\":\"University of Science and Technology of China\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Tao\",\"middleName\":\"\",\"lastName\":\"Wu\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2025-02-04 05:56:34\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-5955283/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-5955283/v1\",\"draftVersion\":[],\"editorialEvents\":[{\"content\":\"https://doi.org/10.1038/s41567-025-03023-3\",\"type\":\"published\",\"date\":\"2025-09-05T04:00:00+00:00\"}],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":79413682,\"identity\":\"88e9997e-d827-4fc1-ad80-c76fb596d2c9\",\"added_by\":\"auto\",\"created_at\":\"2025-03-28 06:48:24\",\"extension\":\"jpg\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":78533,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eStructure and physical properties of La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e.\\u003c/strong\\u003e \\u003cstrong\\u003e(a):\\u003c/strong\\u003e Crystal structure model of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e (left panel) and the stacking units of the monolayer and bilayer NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedrons (right panel) solved from the single-crystal X-ray diffraction data. The bond angle of Ni2-O-Ni2 in the bilayer subslab along the \\u003cem\\u003ec\\u003c/em\\u003e-axis direction is 180°. \\u003cstrong\\u003e(b):\\u003c/strong\\u003e Cross-sectional STEM image of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e along the [110] direction. There are clear monolayer (denoted as ‘1’) and bilayer (denoted as ‘2’) subslab stacking along the \\u003cem\\u003ec\\u003c/em\\u003e-axis direction. The overlaid crystal structure model fits well with the STEM-HAADF image (left panel). The right panel shows the line intensity profile for the image shown in the left panel. \\u003cstrong\\u003e(c):\\u003c/strong\\u003e Powder XRD pattern (blue circles) collected by gridding several microcrystals of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e at a moderate pressure of 1.2 GPa with a wavelength of 0.4834 Å. Adopting the Rietveld refinement method, the powder XRD pattern can be well fitted (red lines) via the structural model shown in (a). The blue lines indicate the difference between the observed and calculated data. The short green vertical lines indicate the calculated diffraction peak positions. \\u003cstrong\\u003e(d):\\u003c/strong\\u003e The temperature-dependent resistivity curve of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e at a small pressure (3.5 GPa) on the DAC when helium gas is used as the pressure transmitting medium. The inset shows the sample connected with the gold electrodes inside the gasket hole. There is a large hump at approximately 170 K in the \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curve, which resembles that of the previously reported electrical transport data collected on powder samples at ambient pressure. \\u003cstrong\\u003e(e):\\u003c/strong\\u003e Temperature-dependent magnetic torque data (\\u003cem\\u003et\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e)) for La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e at various angles. There is a kink at approximately 170 K in the \\u003cem\\u003et\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curve, which is consistent with the anomaly in the \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curve shown in (d). These results indicate a possible DW transition in La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e at approximately 170 K.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"1.jpg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-5955283/v1/c14edb5c59fe8e73ef1cb926.jpg\"},{\"id\":79413681,\"identity\":\"9cf1da57-d0be-4adc-b27a-956f4a46d064\",\"added_by\":\"auto\",\"created_at\":\"2025-03-28 06:48:24\",\"extension\":\"jpg\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":69761,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eElectrical transport properties of La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e single crystals under various pressures for three samples, S2, S3 and S4.\\u003c/strong\\u003e \\u003cstrong\\u003e(a):\\u003c/strong\\u003e \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curves for La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e (S2) in a relatively lower pressure range (8.9–10.8 GPa).\\u003cstrong\\u003e (b):\\u003c/strong\\u003e \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curves for La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11 \\u003c/sub\\u003e(S2),\\u003csub\\u003e \\u003c/sub\\u003ewhere superconductivity begins\\u003csub\\u003e \\u003c/sub\\u003eto occur. \\u003cstrong\\u003e(c):\\u003c/strong\\u003e \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curves of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e (S3) with zero resistance at ~ 40 K at pressures above 18.2 GPa. \\u003cstrong\\u003e(d):\\u003c/strong\\u003e Enlarged view of (c), where the \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e is defined graphically. \\u003cstrong\\u003e(e):\\u003c/strong\\u003e \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curves for La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e (S4) under various magnetic fields along the \\u003cem\\u003ec\\u003c/em\\u003e-axis direction. The onset \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e is quickly suppressed to a lower temperature with increasing magnetic field. The inset shows the \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curve at 23.5 GPa without applying the magnetic field for the La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e crystal (S4), which has similar electrical transport behavior to that of sample S3 and shows a \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e at ~64 K and a \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003ezero\\u003c/sup\\u003e at ~54 K. \\u003cstrong\\u003e(f): \\u003c/strong\\u003eThe upper critical field extracted from (e). There is an obvious positive curvature in the \\u003cem\\u003eH\\u003c/em\\u003e\\u003csub\\u003ec2\\u003c/sub\\u003e-\\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e curve. The upper critical field at the zero-temperature limit is fitted via the two-band model at the clean limit with the equation \\u003cem\\u003eH\\u003c/em\\u003e\\u003csub\\u003ec2\\u003c/sub\\u003e(T) = \\u003cem\\u003eH\\u003c/em\\u003e\\u003csub\\u003ec2\\u003c/sub\\u003e (0)×(1 – (\\u003cem\\u003eT\\u003c/em\\u003e/\\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e))\\u003csup\\u003e1+𝛼\\u003c/sup\\u003e\\u003csub\\u003e, \\u003c/sub\\u003ewhere \\u003cem\\u003eH\\u003c/em\\u003e\\u003csub\\u003ec2\\u003c/sub\\u003e (0) and 𝛼 are fitting parameters\\u003csup\\u003e21\\u003c/sup\\u003e.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"2.jpg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-5955283/v1/e564e1c36178677076baf250.jpg\"},{\"id\":79413685,\"identity\":\"168d7989-a3f0-4434-a4e3-e77ab8ffe4c1\",\"added_by\":\"auto\",\"created_at\":\"2025-03-28 06:48:24\",\"extension\":\"jpg\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":94993,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eStructural evolution of the La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e single crystal with pressure.\\u003c/strong\\u003e \\u003cstrong\\u003e(a):\\u003c/strong\\u003e Powder XRD patterns of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e under various pressures. \\u003cstrong\\u003e(b):\\u003c/strong\\u003e Enlarged view of (a) at the 2\\u003cem\\u003eϴ\\u003c/em\\u003e range of 9.2–11.2°, where the diffraction peaks of (200) and (020) gradually merged with increasing pressure. \\u003cstrong\\u003e(c):\\u003c/strong\\u003e Calculated lattice parameters of the \\u003cem\\u003ea-\\u003c/em\\u003e and \\u003cem\\u003eb\\u003c/em\\u003e-axes for La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e under various pressures. The values of \\u003cem\\u003ea\\u003c/em\\u003e and \\u003cem\\u003eb\\u003c/em\\u003e decrease quickly and become equal at approximately 4.5 GPa (dashed line).\\u003cstrong\\u003e (d): \\u003c/strong\\u003eCalculated lattice parameters of the \\u003cem\\u003ec\\u003c/em\\u003e-axis and specific cell volume for one La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e molecule (\\u003cem\\u003eV\\u003c/em\\u003e/\\u003cem\\u003eZ\\u003c/em\\u003e) under various pressures, where \\u003cem\\u003eV\\u003c/em\\u003e is the cell volume and \\u003cem\\u003eZ\\u003c/em\\u003e is the molecule number for one crystal cell. The dashed line is located at 4.5 GPa.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"3.jpg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-5955283/v1/4d8cee585ea1c87afe38c6cb.jpg\"},{\"id\":79414197,\"identity\":\"96dc6b36-ff25-4147-8c2f-f947e18c66e1\",\"added_by\":\"auto\",\"created_at\":\"2025-03-28 06:56:24\",\"extension\":\"jpg\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":36501,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003ePhase diagram of the hybrid \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e 1212 nickelates with the chemical formula La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e. (a):\\u003c/strong\\u003e Pressure-dependent crystal structure, DW transition and \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e\\u003csub\\u003e \\u003c/sub\\u003efor the La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e single crystal. The dotted dashed line separates the crystal structures of \\u003cem\\u003eCmmm\\u003c/em\\u003e and \\u003cem\\u003eP4/mmm\\u003c/em\\u003e. The gray and red areas indicate the density wave regime (DW) and superconductivity regime (SC), respectively. \\u003cstrong\\u003e(b): \\u003c/strong\\u003eThe \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e and the average in-plane lattice (\\u003cem\\u003ea\\u003c/em\\u003e\\u003csub\\u003ep\\u003c/sub\\u003e) relationship for La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"4.jpg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-5955283/v1/30a87c37e9695a8fb28f7773.jpg\"},{\"id\":90711759,\"identity\":\"54d04ff4-ac45-44c8-8693-0e1567386f96\",\"added_by\":\"auto\",\"created_at\":\"2025-09-06 07:08:41\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":2002516,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-5955283/v1/36b9dbdf-f049-49dc-b7ef-b097dd71a57f.pdf\"},{\"id\":79413686,\"identity\":\"f8f7995b-2eb3-4113-ac86-9598bce4c061\",\"added_by\":\"auto\",\"created_at\":\"2025-03-28 06:48:24\",\"extension\":\"docx\",\"order_by\":1,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":4890697,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"ExtendedFiguresandTables.docx\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-5955283/v1/21625bbbb5c36cd4ecd71d13.docx\"}],\"financialInterests\":\"There is \\u003cb\\u003eNO\\u003c/b\\u003e Competing Interest.\",\"formattedTitle\":\"Superconductivity of the hybrid Ruddlesden‒Popper La5Ni3O11 single crystals under high pressure\",\"fulltext\":[{\"header\":\"Full Text\",\"content\":\"\\u003cp\\u003eSince the discovery of superconductivity in cuprates, exploring high-temperature superconducting materials with similar crystal and electronic structures has become an important research direction\\u003csup\\u003e1,2,3,4,5,6,7\\u003c/sup\\u003e. A major breakthrough in this field was made in the infinite-layer nickelate Nd\\u003csub\\u003e0.8\\u003c/sub\\u003eSr\\u003csub\\u003e0.2\\u003c/sub\\u003eNiO\\u003csub\\u003e2\\u0026nbsp;\\u003c/sub\\u003ethin films with a superconducting transition temperature (\\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e) of 9--15 K in 2019\\u003csup\\u003e8\\u003c/sup\\u003e. Motivated by this groundbreaking finding, the Ruddlesden‒Popper (\\u003cem\\u003eRP\\u003c/em\\u003e) phase nickelates \\u003cem\\u003eR\\u003c/em\\u003e\\u003csub\\u003en+1\\u003c/sub\\u003eNi\\u003csub\\u003en\\u003c/sub\\u003eO\\u003csub\\u003e3n+1\\u003c/sub\\u003e (\\u003cem\\u003eR\\u0026nbsp;\\u003c/em\\u003e= rare earth) with n = 2 and n = 3 are reported to exhibit superconductivity under pressure\\u003csup\\u003e9,10,11,12,13\\u003c/sup\\u003e, which largely expands the family of nickelate superconductors. In these \\u003cem\\u003eRP\\u003c/em\\u003e nickelates \\u003cem\\u003eR\\u003c/em\\u003e\\u003csub\\u003en+1\\u003c/sub\\u003eNi\\u003csub\\u003en\\u003c/sub\\u003eO\\u003csub\\u003e3n+1\\u003c/sub\\u003e (\\u003cem\\u003eR\\u0026nbsp;\\u003c/em\\u003e= rare earth), the multilayer perovskite structure (\\u003cem\\u003eR\\u003c/em\\u003eNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003en\\u003c/sub\\u003e is believed to be the fundamental building block for superconductivity. Clarifying the role of the multilayer perovskite structure (\\u003cem\\u003eR\\u003c/em\\u003eNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003en\\u003c/sub\\u003e in the superconducting phase is important for building a theoretical model for the superconducting mechanism. At ambient pressure, the NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedron in the (\\u003cem\\u003eR\\u003c/em\\u003eNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003en\\u003c/sub\\u003e structure is distorted and tilted, which leads to an orthorhombic structure. Moreover, in such an orthorhombic structure phase, a density-wave (DW) transition is widely observed at approximately 130--150 K in \\u003cem\\u003eRP\\u003c/em\\u003e nickelates with n = 2 and 3, which involves both spin and charge density wave orders\\u003csup\\u003e14\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e15\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e16\\u003c/sup\\u003e. With increasing pressure, the distortion and tilting of the NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedron are strongly suppressed, and a pressure-induced structural transition from an orthorhombic structure to a tetragonal structure occurs at approximately 15 GPa\\u003csup\\u003e9,12\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e11\\u003c/sup\\u003e. Previous high-pressure transport measurements suggest that the DW transition is also suppressed with increasing pressure, and the pressure-dependent phase diagram of superconductivity and density-wave order suggests a possible competing scenario with a second-order manner\\u0026nbsp;\\u003csup\\u003e9\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e17\\u003c/sup\\u003e.\\u003c/p\\u003e\\n\\u003cp\\u003eIn addition to RP-phase nickelates, hybrid \\u003cem\\u003eRP\\u003c/em\\u003e-phase nickelates has been also reported\\u003csup\\u003e18\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e19\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e20\\u003c/sup\\u003e. Hybrid \\u003cem\\u003eRP\\u003c/em\\u003e-phase nickelates are formed by alternative stacking of different \\u003cem\\u003eRP\\u003c/em\\u003e phases along the \\u003cem\\u003ec\\u003c/em\\u003e axis. To date, two hybrid \\u003cem\\u003eRP\\u003c/em\\u003e-phase nickelates have been reported: the 1313 phase, with a chemical formula of La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7,\\u003c/sub\\u003e and the 1212 phase, with a chemical formula of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e\\u003csup\\u003e18\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e19\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e20\\u003c/sup\\u003e. In the 1313 phase, the (LaNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e layer and La\\u003csub\\u003e2\\u003c/sub\\u003eNiO\\u003csub\\u003e4\\u003c/sub\\u003e layer alternately stack along the \\u003cem\\u003ec\\u003c/em\\u003e axis and are separated by the LaO layer. Previous high-pressure transport measurements suggest possible high-temperature superconductivity in the 1313 phase, with an onset transition temperature of approximately 80 K\\u003csup\\u003e20\\u003c/sup\\u003e. Since there are no reports on superconductivity in the La\\u003csub\\u003e2\\u003c/sub\\u003eNiO\\u003csub\\u003e4\\u003c/sub\\u003e phase, the superconducting pairing should come from the (LaNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e layer. This result further supports the use of the multilayer perovskite structure (\\u003cem\\u003eR\\u003c/em\\u003eNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003en\\u003c/sub\\u003e as the fundamental building block for superconductivity. However, there is a hot debate on the superconducting phase for pressurized superconductors with the chemical formula La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u0026nbsp;\\u003c/sub\\u003eand the onset transition temperature\\u003cem\\u003e\\u0026nbsp;T\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e\\u0026nbsp;\\u003c/em\\u003e= 80 K because this chemical formula can share either the \\u003cem\\u003eRP\\u003c/em\\u003e phase \\u003cem\\u003eR\\u003c/em\\u003e\\u003csub\\u003en+1\\u003c/sub\\u003eNi\\u003csub\\u003en\\u003c/sub\\u003eO\\u003csub\\u003e3n+1\\u0026nbsp;\\u003c/sub\\u003ewith n = 2 or the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1313 phase, which is formed by alternative stacking of the (LaNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e layer and the La\\u003csub\\u003e2\\u003c/sub\\u003eNiO\\u003csub\\u003e4\\u003c/sub\\u003e layer along the \\u003cem\\u003ec\\u003c/em\\u003e axis. Furthermore, \\u003cem\\u003eT\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u0026nbsp;\\u003c/sup\\u003e\\u003c/em\\u003e= 80 K in the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1313 phase seems to conflict with the reported superconductivity with a \\u003cem\\u003eT\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e\\u003c/em\\u003e of less than 30 K in the pressurized \\u003cem\\u003eRP\\u003c/em\\u003e trilayer nickelate La\\u003csub\\u003e4\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e10\\u003c/sub\\u003e\\u003csup\\u003e10,11,12,13\\u003c/sup\\u003e; more experiments on the origin of superconductivity in the 1313 phase are needed. Because the multilayer perovskite structure (\\u003cem\\u003eR\\u003c/em\\u003eNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003en\\u003c/sub\\u003e serves as the fundamental building block for superconductivity, high-temperature superconductivity should be expected in the 1212 phase under pressure. In the 1212 phase, as shown in Fig. 1a, the single-layer and bilayer blocks of NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedron alternately stack along the \\u003cem\\u003ec\\u003c/em\\u003e axis, forming the so-called hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate\\u003csup\\u003e18\\u003c/sup\\u003e. In this work, we perform a systematic study on the pressure-dependent evolution of the electronic state in a hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate single crystal with a chemical formula of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e. High-pressure transport measurements using helium gas as the pressure transmitting medium revealed an unambiguous superconducting transition above ~ 12 GPa. The optimal superconducting transition temperature\\u0026nbsp;of\\u0026nbsp;a \\u003cem\\u003eT\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonset\\u003c/sup\\u003e\\u003c/em\\u003e of ~ 64 K and a zero-resistivity temperature (\\u003cem\\u003eT\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003ezero\\u003c/sup\\u003e\\u003c/em\\u003e) of ~ 54 K\\u0026nbsp;is achieved at\\u0026nbsp;approximately 21 GPa. In addition, the pressure-dependent evolution of the superconductivity, DW transition and structure are also mapped out.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eStructure and density-wave transition at nearly ambient pressure\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate single crystal was synthesized through a melt‒salt method (see Methods for details). After the flux was dissolved in water, the product was filtered with 400-mesh (~38.5 µm) sieves. A single crystal with typical dimensions of 0.1×0.1×0.02 mm was carefully checked via a four-circle diffractometer. Fig. 1a shows the crystal structure model of the as-grown hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate single crystal (left panel) determined from single-crystal X-ray diffraction data, where single-layer and bilayer perovskite-like NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedrons alternately stack along the \\u003cem\\u003ec\\u003c/em\\u003e-axis direction, as previously reported\\u003csup\\u003e18\\u003c/sup\\u003e. The space group is determined to be \\u003cem\\u003eCmmm\\u003c/em\\u003e, which is different from the previously reported \\u003cem\\u003eImmm\\u003c/em\\u003e\\u003csup\\u003e18\\u003c/sup\\u003e. We note that the similar compound “1313” phase nickelate, where single-layer and trilayer blocks of NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedrons stack alternately along the \\u003cem\\u003ec\\u003c/em\\u003e-axis direction, also adopts a \\u003cem\\u003eCmmm\\u003c/em\\u003e space group\\u003csup\\u003e19\\u003c/sup\\u003e.\\u0026nbsp;The structure of the hybrid \\u003cem\\u003eRP\\u0026nbsp;\\u003c/em\\u003e1212 nickelate is also confirmed by atomically resolved scanning transmission electron microscopy (STEM) images, where the alternate stacking of single-layer and bilayer blocks of NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedrons is clearly observed in Fig. 1b. The overlaid crystal structure model fits well with the STEM-HAADF image (Fig. 1b left panel).\\u0026nbsp;By grinding several pieces of hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate single crystals, powder X-ray diffraction (XRD) patterns were collected at the Shanghai Synchrotron Radiation Facility at a wavelength of 0.4834 Å at moderate pressure (1.2 GPa) using helium gas as the pressure transmitting medium. With the Rietveld refinement method, the powder XRD pattern can be well fitted\\u0026nbsp;with the structural model solved from the single-crystal XRD data.\\u0026nbsp;No other \\u003cem\\u003eRP\\u003c/em\\u003e phase was observed in the powder XRD pattern. In the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e-phase nickelate La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e, the out-of-plane Ni-O-Ni angle between the NiO\\u003csub\\u003e6\\u003c/sub\\u003e octahedrons is symmetry constrained to 180° (see Fig. 1a and Table S1), which is different from the value of 168° in La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e with the \\u003cem\\u003eAmam\\u003c/em\\u003e space group at ambient pressure. The out-of-plane Ni-O-Ni angle was previously thought to be critical for interlayer coupling between NiO planes, which favours superconductivity under high pressure. More detailed crystal data, structure refinements and bond angles are shown in Extended Data Table S1 and Extended Data Fig. 1. To obtain good electric contact, the temperature-dependent resistivity curve (\\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e)) for the as-grown microcrystal was measured on a DAC with a small pressure (~3.5 GPa) (see the inset of Fig. 1d). As shown in Fig. 1d, the resistance curve (\\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e)) exhibits a large hump at approximately 170 K, which is consistent with a previous report on powder samples at ambient pressure\\u003csup\\u003e18\\u003c/sup\\u003e. The anomaly in the resistivity curve is possibly due to a DW transition, which is similar to the other \\u003cem\\u003eRP\\u003c/em\\u003e phase nickelates and the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e “1313” phase nickelate\\u003csup\\u003e14\\u003c/sup\\u003e\\u003csup\\u003e,\\u003c/sup\\u003e\\u003csup\\u003e15\\u003c/sup\\u003e\\u003csup\\u003e,19\\u003c/sup\\u003e. Magnetic torque measurements conducted on the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate microcrystal (Fig. 1e) confirmed a DW transition at ~170 K, which corresponds to the temperature at the maximum of the hump in the \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curve. We note that no obvious nonstoichiometry is observed on the basis of the EDX analysis (Extended Data Fig. 2) and the refinement of the single-crystal XRD data (see Methods).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePressure-induced superconductivity\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe electrical transport properties of the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate under various pressures were collected on a DAC using helium gas as the pressure transmitting medium\\u003csup\\u003e11\\u003c/sup\\u003e. Notably, the homogeneity of the pressure environment is very important for electrical transport measurements under pressure, especially for the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate. Owing to the large volume shrinkage of helium gas under high pressure, good electric contact is quite challenging in practice, and realistic electric contacts usually work well only within a limited pressure range. Here, we successfully measure the electrical transport in different pressure ranges on three pieces of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e single crystals, S2, S3 and S4, which are selected from the same batch. The electric contacts for sample S2 are good only for electrical measurements at relatively low pressures (below ~ 15 GPa), and the electric contacts for samples S3 and S4 are good only for electrical measurements at relatively high pressures (above ~ 15 GPa). For sample S2, the resistance at room temperature gradually decreases at a relatively low pressure (8.9–10.8 GPa, Fig. 2a), and the overall temperature-dependent behavior is similar to that at 3.5 GPa (Fig. 1d). When the applied pressure further increases above 11.7 GPa, although the DW transition temperature remains almost unchanged, the signature of the DW transition in transport is strongly suppressed and completely fades above ~ 13 GPa (Fig. 2b). This result suggests a pressure-induced first-order phase transition for the DW order (Fig. 4a). At ~ 11.7 GPa, a sharp drop in the \\u003cem\\u003eR\\u003c/em\\u003e(\\u003cem\\u003eT\\u003c/em\\u003e) curve indicates the emergence of superconductivity, with a \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonest\\u003c/sup\\u003e of 17.9 K (Fig. 2b). Above 11.7 GPa, the value of \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonest\\u0026nbsp;\\u003c/sup\\u003econtinuously increases and reaches the optimal superconductivity, with the highest \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonest\\u003c/sup\\u003e value of ~ 64 K occurring at ~ 21.5 GPa (Figs. 2c and 2d, sample S3). As shown in Fig. 2d, there is a step-like transition at approximately 50 K due to possible inhomogeneity of the pressure environment, which leads to a zero-resistance temperature of only 42 K in sample S3 (Extended Data Fig. 4a). By improving the homogeneity of the pressure environment, we finally obtain a \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonest\\u003c/sup\\u003e of ~ 64 K and a \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003ezero\\u003c/sup\\u003e of ~ 54 K for sample S4 (Fig. 2e), which are among the highest reported zero-resistance temperatures and the sharpest superconducting transitions for nickelate superconductors. As shown in Fig. 2e and Extended Data Fig. 4, we studied the superconducting transition under different magnetic fields perpendicular to the ab planes. The upper critical field (\\u003cem\\u003eH\\u003csub\\u003ec2\\u003c/sub\\u003e\\u003c/em\\u003e) is extracted with different criteria. As shown in Fig. 2f, there is a positive curvature in the \\u003cem\\u003eH\\u003c/em\\u003e\\u003csub\\u003ec2\\u003c/sub\\u003e-\\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e curve, which cannot be explained by a single-band Ginzburg–Landau (GL) model. Here, we use a two-band model at the clean limit to fit the upper critical field, which works quite well and yields \\u003cem\\u003eH\\u003csub\\u003ec2\\u003c/sub\\u003e\\u003c/em\\u003e values of 20--28 T at the zero-temperature limit\\u003csup\\u003e21\\u003c/sup\\u003e. In La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e with the \\u003cem\\u003eAmam\\u003c/em\\u003e space group, the upper critical field along the out-of-plane direction is ~180 T at 18.9 GPa\\u0026nbsp;\\u003csup\\u003e9\\u003c/sup\\u003e, which is much greater than that in our case. This low upper critical field in the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate is also confirmed in another single-crystal sample (Extended data Fig. 4b). Above 20 GPa, the superconducting transition temperature starts to slightly decrease with increasing pressure up to 25.2 GPa.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eStructural transition under pressure\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eTo further understand the electrical transport behavior under pressure, we measured the powder XRD patterns under various pressures up to 30.5 GPa for the hybrid 1212 nickelate by grinding several pieces of microcrystals with helium gas as the pressure transmitting medium at the Shanghai Synchrotron Radiation Facility at a wavelength of 0.4834 Å. Fig. 3 and Extended Data Fig. 5 summarize the main results. At ambient pressure, the 1212 nickelate microcrystal adopts an orthorhombic structure with a space group of \\u003cem\\u003eCmmm\\u003c/em\\u003e, which is characterized by the splitting of the (020) and (200) diffraction peaks. With increasing pressure, the diffraction peaks of (020) and (200) gradually merged, which indicates a structural transition from the orthorhombic phase to the tetragonal phase below 5.8 GPa (Fig. 3b). In the crystals of La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e with the \\u003cem\\u003eAmam\\u003c/em\\u003e space group and La\\u003csub\\u003e4\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e10\\u003c/sub\\u003e, the pressure at which the structure transitions into the tetragonal phase is approximately 14 GPa, which is much greater than that of the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate\\u0026nbsp;\\u003csup\\u003e9,12\\u003c/sup\\u003e.\\u0026nbsp;The refinement of the powder XRD pattern at 5.8 GPa gives a tetragonal phase structure with a space group of \\u003cem\\u003eP4/mmm\\u003c/em\\u003e (Extended data Fig. 5b), which is similar to the case of the hybrid \\u003cem\\u003eRP\\u0026nbsp;\\u003c/em\\u003e1313 phase under high pressure\\u003csup\\u003e20\\u003c/sup\\u003e. The tetragonal phase structure is maintained at 30.5 GPa. More detailed evolution of the lattice parameters and cell volume are refined and shown in Figs. 3c-d, where the lattice parameters show a progressive decrease under pressure. A careful analysis of the evolution of the lattice parameters of the \\u003cem\\u003ea-\\u003c/em\\u003e and \\u003cem\\u003eb\\u003c/em\\u003e-axes indicates that the critical pressure for the structural transition is approximately 4.5 GPa (Fig. 3c).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePressure-dependent phase diagram\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eIn Fig. 4a, we summarize the results of high-pressure transport and XRD diffraction into a pressure-dependent phase diagram. As the pressure increases, the crystalline structure of the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate transitions from a low-pressure orthorhombic phase (\\u003cem\\u003eCmmm\\u003c/em\\u003e) to a high-pressure tetragonal phase (\\u003cem\\u003eP4/mmm\\u003c/em\\u003e) at a critical pressure of ~ 4.5 GPa, which is much lower than that of La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e and La\\u003csub\\u003e4\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e10\\u003c/sub\\u003e (~ 14 GPa)\\u003csup\\u003e9,11\\u003c/sup\\u003e. In contrast to previous high-pressure transport measurements on La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e and La\\u003csub\\u003e4\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e10\\u003c/sub\\u003e, the density-wave transition in 1212 nickelate is quite robust during the structural transition and is continuously enhanced with increasing pressure. Notably, previous muon spin rotation (μSR) and nuclear magnetic resonance (NMR) experiments on pressurized La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e revealed a pressure-enhanced spin-density-wave (SDW) transition\\u003csup\\u003e14\\u003c/sup\\u003e\\u003csup\\u003e,15\\u003c/sup\\u003e. We speculate that the DW transition in the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate is also related to a similar SDW transition, which needs further experimental investigation in the future. Above 11.7 GPa, the superconducting phase emerges with dome-like pressure-dependent behavior. Our present results indicate strong competition between possible SDW order and superconductivity. They are connected via a first-order phase transition in the pressure-dependent phase diagram. Finally, we also studied the relationship between \\u003cem\\u003eT\\u003csub\\u003ec\\u003c/sub\\u003e\\u003c/em\\u003e and the average in-plane lattice () in the hybrid \\u003cem\\u003eRP\\u0026nbsp;\\u003c/em\\u003e1212 nickelate. As shown in Fig. 4b, the relationship between the \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e and the average in-plane lattice parameter in 1212 nickelate is similar to that in pressurized La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e \\u003csup\\u003e9,\\u0026nbsp;\\u003c/sup\\u003e\\u003csup\\u003e22\\u003c/sup\\u003e, in which pressure-induced superconductivity appears in the structure with a relatively small\\u0026nbsp;\\u0026nbsp;(\\u0026lt; 3.77 Å). This result suggests that the multilayer perovskite structure (\\u003cem\\u003eR\\u003c/em\\u003eNiO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e is the fundamental building block for superconductivity. Very recently, by utilizing compressed strain through a substrate, ambient-pressure superconductivity has been observed in La\\u003csub\\u003e3-x\\u003c/sub\\u003ePr\\u003csub\\u003ex\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e films\\u0026nbsp;\\u003csup\\u003e23\\u003c/sup\\u003e\\u003csup\\u003e,\\u0026nbsp;\\u003c/sup\\u003e\\u003csup\\u003e24\\u003c/sup\\u003e. The relationship between \\u003cem\\u003eT\\u003csub\\u003ec\\u003c/sub\\u003e\\u003c/em\\u003e and the average in-plane lattice in these La\\u003csub\\u003e3-x\\u003c/sub\\u003ePr\\u003csub\\u003ex\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e films also shows a similar behavior as that of the bulk samples under pressure. Here, the observation of pressure-induced superconductivity in the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e 1212 nickelate suggests an alternative route to achieve ambient-pressure superconductivity in the hybrid \\u003cem\\u003eRP\\u003c/em\\u003e nickelates. The average in-plane lattice parameter of La\\u003csub\\u003e2\\u003c/sub\\u003eNiO\\u003csub\\u003e4\\u003c/sub\\u003e is approximately 3.85–3.87 Å, which is relatively larger than the average in-plane lattice parameter of La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e (\\u003cem\\u003ea\\u003c/em\\u003e\\u003csub\\u003ep\\u003c/sub\\u003e =3.835 Å)\\u0026nbsp;\\u003csup\\u003e25\\u003c/sup\\u003e. If we can replace the La\\u003csub\\u003e2\\u003c/sub\\u003eNiO\\u003csub\\u003e4\\u003c/sub\\u003e layer with another \\u003cem\\u003eRP\\u003c/em\\u003e layer with a smaller \\u003cem\\u003ea\\u003c/em\\u003e\\u003csub\\u003ep\\u003c/sub\\u003e, it might be possible to tune the value of \\u003cem\\u003ea\\u003c/em\\u003e\\u003csub\\u003ep\\u003c/sub\\u003e to the superconducting region, as shown in Fig. 4b. This deserves further experimental exploration of new hybrid \\u003cem\\u003eRP\\u003c/em\\u003e nickelates.\\u003c/p\\u003e\\n\\u003cp\\u003eIn summary, by performing high-pressure transport measurements with helium gas as the pressure transmitting medium, we discovered pressure-induced superconductivity with an optimal \\u003cem\\u003eT\\u003c/em\\u003e\\u003csub\\u003ec\\u003c/sub\\u003e\\u003csup\\u003eonest\\u003c/sup\\u003e of ~ 64 K in a hybrid RP 1212 nickelate single crystal with the chemical formula La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e. In contrast to previously reported pressure-induced superconductivity in La\\u003csub\\u003e3\\u003c/sub\\u003eNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e and La\\u003csub\\u003e4\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e10\\u003c/sub\\u003e, the ambient-pressure DW order in the hybrid RP 1212 nickelate is quite robust against pressure, and the pressure-dependent phase diagram demonstrates a first-order phase transition between the low-pressure DW order and the high-pressure superconductivity. In addition, a structural transition from the orthorhombic phase to the tetragonal phase is also revealed at 4.5 GPa. Finally, this work also suggests the potential for realizing ambient-pressure superconductivity via sophisticated structural design of hybrid \\u003cem\\u003eRP\\u003c/em\\u003e nickelates.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eData availability\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe data that support the findings of this study are available from the corresponding author upon request.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCode availability\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe codes that support the findings of this study are available from the corresponding author upon request.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eWe acknowledge fruitful discussions with Ho-kwang Mao, Zhengyu Wang and Ziji Xiang. We also thank Zhongliang Zhu, Fujun Lan, Yuxin Liu, and Hongbo Lou for their experimental assistance. This work is supported by the National Natural Science Foundation of China (Grant Nos. 12494592, 12488201, 11888101, 12034004, 12161160316, 12325403, and 12204448), the National Key R\\u0026amp;D Program of the MOST of China (Grant No. 2022YFA1602601), the Chinese Academy of Sciences under contract No. JZHKYPT-2021-08, the CAS Project for Young Scientists in Basic Research (Grant No. YBR-048), and the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800).\\u0026nbsp;D.P. and Q.Z. acknowledge the financial support from the Shanghai Science and Technology Committee (Grant No. 22JC1410300) and Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (Grant No.22dz2260800). A portion of this research used resources at the beamline 17UM of the Shanghai synchrotron radiation facility.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthor contributions\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eX.H.C. conceived the research project and coordinated the experiments. M.Z.S. grew the single crystals and performed the structural characterization at ambient pressure with the help of R.Q.W. and M.D.; H.P.L. and K.B.F. measured the magnetic torque data; S.H.Y. and B.H.G. collected the TEM images; D.P. performed the resistance measurements using helium gas as the pressure-transmitting medium under pressure with the help of Q.S.Z.; D.P., Z.F.X. and Y.Z.W. performed the synchrotron powder diffraction measurements and analysis under high pressure using helium gas as the pressure-transmitting medium with help from Q.S.Z. and Z.D.Z.; M.Z.S., D.P., J.J.Y., T.W. and X.H.C. analysed the data; M.Z.S., D.P., K.B.F., T.W. and X.H.C. wrote the paper with inputs from all the authors.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n\\u003cli\\u003eBednorz, J. G. \\u0026amp; M\\u0026uuml;ller, K. A. 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Superconductivity and normal-state transport in compressively strained La\\u003csub\\u003e2\\u003c/sub\\u003ePrNi\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e7\\u003c/sub\\u003e thin films. Preprint at https://doi.org/10.48550/arXiv.2501.08022 (2025).\\u003c/li\\u003e\\n\\u003cli\\u003eZhou, G. et al. Ambient-pressure superconductivity onset above 40 K in bilayer nickelate ultrathin films. Preprint at https://doi.org/10.48550/arXiv.2412.16622 (2024).\\u003c/li\\u003e\\n\\u003cli\\u003eThanh, TD. et al. Structure, Magnetic, and Electrical Properties of La\\u003csub\\u003e2\\u003c/sub\\u003eNiO\\u003csub\\u003e4+\\u0026delta;\\u003c/sub\\u003e Compounds. \\u003cem\\u003eIEEE Trans. Magn.\\u003c/em\\u003e \\u003cstrong\\u003e53\\u003c/strong\\u003e, 1-4 (2017).\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"},{\"header\":\"Methods\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eSample growth:\\u003c/strong\\u003e The La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003cstrong\\u003e\\u003csub\\u003e11\\u003c/sub\\u003e\\u003c/strong\\u003e crystals were grown via a melt salt method. First, the La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003ex\\u003c/sub\\u003e precursor (P) was obtained via a standard sol‒gel process. Specifically, the La source (lanthanum nitrate hexahydrate), Ni source (nickel (II) nitrate hexahydrate) and complexing agent (citric acid, CA) were dissolved in water at a molar ratio of La:Ni:CA= 5:3:8. The above solution was preheated at 140 °C for approximately 24 h to obtain a dry gel, which was then transferred into a muffle furnace where the temperature was slowly increased to 400 °C and maintained for another 10 h. Second, the above precursor (P) was mixed with a salt flux (NaCl/KCl mixture) at a mass ratio of P:NaCl:KCl = 1:14:16 and loaded into a corundum crucible. The corundum crucible was heated to 1150 °C for 10 h, maintained at this temperature for 48 h, and then slowly cooled to 1110 °C within 7 days. Microcrystals with a typical size of 0.1×0.1×0.02 mm were obtained after the flux was washed with water.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eStructural and composition characterization at ambient pressure:\\u003c/strong\\u003e The as-grown microcrystal was mounted on the sample holder using high-vacuum silicon grease as the glue. Single-crystal X-ray diffraction (SC-XRD) data were collected on a four-circle diffractometer (Rigaku, XtaLAB PRO 007HF) with Cu\\u0026nbsp;\\u003cem\\u003eKα\\u003c/em\\u003e radiation at the Core Facility Center for Life Sciences, USTC. The structure was solved and refined via Olex-2 with the ShelXT and ShelXL packages. The detailed structural data are shown in Table S1. All the crystals were first checked via a four-circle diffractometer before they were used to conduct further physical measurements. Energy-dispersive X-ray spectroscopy (EDX) equipped with a scanning electron microscope (SEM, Hitachi SU8220) was used to characterize the chemical composition. The element ratio of La:Ni is approximately 1.67:1 (Extended Data Fig. 2). The refinement of the occupancy of the oxygen sites on the basis of the SC-XRD data gives a value of 0.984--1.072, which indicates nearly full occupation of all these oxygen sites. There is only one oxygen site (O3 site, see Fig. 1a) that is smaller than 1. These results indicate negligible nonstoichiometry in the as-grown La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e single crystal. The scanning transmission electron microscopy (STEM) images were collected on a Thermo Fischer Scientific Titan Themis Z microscope with a working voltage of 300 kV.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eMagnetic torque measurement:\\u003c/strong\\u003e Using an SCL piezoresistive cantilever, torque magnetometry data were collected via a physical property measurement system (PPMS, Quantum Design Inc., DynaCool-14T). The sample was carefully attached to the tip of the cantilever, which was fixed on a horizontal rotator. The sample was rotated in the range of\\u0026nbsp;\\u003cem\\u003eq\\u003c/em\\u003e (the angle between the magnetic field vector\\u003cem\\u003e\\u0026nbsp;H\\u0026nbsp;\\u003c/em\\u003e(14T)and the flat plane of the La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e11\\u003c/sub\\u003e crystal) from 0°\\u0026nbsp;to 90°\\u0026nbsp;under isothermal conditions.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eElectrical transport and XRD measurements under high pressure:\\u0026nbsp;\\u003c/strong\\u003eResistance curves for the La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003cstrong\\u003e\\u003csub\\u003e11\\u003c/sub\\u003e\\u003c/strong\\u003esingle crystalsunderhigh pressure were measured in a diamond anvil cell (DAC) using helium gas as the pressure transmitting medium. The pressure was applied, and the mixture was calibrated by shifting the ruby florescence at room temperature. The transport measurements were conducted in a Physical Properties Measurement System (PPMS-9, Quantum Design Inc.). The powder XRD data of La\\u003csub\\u003e5\\u003c/sub\\u003eNi\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003cstrong\\u003e\\u003csub\\u003e11\\u003c/sub\\u003e\\u003c/strong\\u003e under pressure were collected by gridding several pieces of microcrystals at the Shanghai Synchrotron Radiation Facility via an X-ray beam with a wavelength of 0.4834 Å. Helium gas was used as the pressure transmitting medium. The powder XRD data were refined via GSAS software to obtain the lattice parameters under different pressures.\\u003c/p\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":true,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":true,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"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\":\"\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-5955283/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-5955283/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003e\\u003cstrong\\u003eThe discovery of high-temperature superconductivity in La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e2\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e7\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e and La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e4\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e10\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e under high pressure indicates that the Ruddlesden‒Popper (\\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e) phase nickelates \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eR\\u003c/strong\\u003e\\u003c/em\\u003e\\u003csub\\u003e\\u003cstrong\\u003en+1\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003en\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3n+1\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e (\\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eR \\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e= rare earth) is a new material family for high-temperature superconductivity. Exploring the superconductivity of other \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e or hybrid \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e phase nickelates under high pressure has become an urgent and interesting issue. Here, we report a novel hybrid \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e nickelate superconductor of La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e. The hybrid \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e nickelate La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e is formed by alternative stacking of La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e2\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e7\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e with n=2 and La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e2\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNiO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e4\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e with n=1 along the \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003ec\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e axis. The transport and magnetic torque measurements indicate a density-wave transition at approximately 170 K near ambient pressure, which is highly similar to both La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e2\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e7\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e and La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e4\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e10\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e. With increasing pressure, high-pressure transport measurements reveal that the density-wave transition temperature (\\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eT\\u003c/strong\\u003e\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e\\u003cstrong\\u003eDW\\u003c/strong\\u003e\\u003c/em\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e) continuously increases to approximately 210 K with increasing pressure up to 12 GPa before the appearance of pressure-induced superconductivity, and the density-wave transition abruptly fades out in a first-order manner at approximately 12 GPa. The optimal superconductivity with \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eT\\u003c/strong\\u003e\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e\\u003cstrong\\u003ec\\u003c/strong\\u003e\\u003c/em\\u003e\\u003c/sub\\u003e\\u003csup\\u003e\\u003cem\\u003e\\u003cstrong\\u003eonset\\u003c/strong\\u003e\\u003c/em\\u003e\\u003c/sup\\u003e\\u003cstrong\\u003e = 64 K and \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eT\\u003c/strong\\u003e\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e\\u003cstrong\\u003ec\\u003c/strong\\u003e\\u003c/em\\u003e\\u003c/sub\\u003e\\u003csup\\u003e\\u003cem\\u003e\\u003cstrong\\u003ezero\\u003c/strong\\u003e\\u003c/em\\u003e\\u003c/sup\\u003e\\u003csup\\u003e\\u003cstrong\\u003e \\u003c/strong\\u003e\\u003c/sup\\u003e\\u003cstrong\\u003e= 54 K is achieved at approximately 21 GPa. On the other hand, high-pressure X-ray diffraction experiments reveal a structural phase transition from an orthorhombic structure to a tetragonal structure at approximately 4.5 GPa. In contrast to La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e2\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e7\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e and La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e4\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e10\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e, the pressure-induced structural transition has no significant effect on either the density-wave transition or the superconductivity, suggesting a minor role of lattice degree of freedom in La\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e5\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eNi\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e3\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003eO\\u003c/strong\\u003e\\u003csub\\u003e\\u003cstrong\\u003e11\\u003c/strong\\u003e\\u003c/sub\\u003e\\u003cstrong\\u003e. The present discovery extends the superconducting member in the \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003eRP\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e nickelate family and sheds new light on the superconducting mechanism.\\u003c/strong\\u003e\\u003c/p\\u003e\",\"manuscriptTitle\":\"Superconductivity of the hybrid Ruddlesden‒Popper La5Ni3O11 single crystals under high pressure\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2025-03-28 06:48:20\",\"doi\":\"10.21203/rs.3.rs-5955283/v1\",\"editorialEvents\":[],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"nature-physics\",\"isNatureJournal\":true,\"hasQc\":false,\"allowDirectSubmit\":false,\"externalIdentity\":\"nphys\",\"sideBox\":\"Learn more about [Nature Physics](http://www.nature.com/nphys/)\",\"snPcode\":\"\",\"submissionUrl\":\"\",\"title\":\"Nature Physics\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"ejp\",\"reportingPortfolio\":\"Nature Research\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false}}],\"origin\":\"\",\"ownerIdentity\":\"4bc0f8c8-d0f6-41d9-93ce-6b9ef3feadb3\",\"owner\":[],\"postedDate\":\"March 28th, 2025\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"published-in-journal\",\"subjectAreas\":[{\"id\":45186589,\"name\":\"Physical sciences/Physics/Condensed-matter physics/Superconducting properties and materials\"},{\"id\":45186590,\"name\":\"Physical sciences/Materials science/Condensed-matter physics/Superconducting properties and materials\"}],\"tags\":[],\"updatedAt\":\"2025-09-06T07:08:36+00:00\",\"versionOfRecord\":{\"articleIdentity\":\"rs-5955283\",\"link\":\"https://doi.org/10.1038/s41567-025-03023-3\",\"journal\":{\"identity\":\"nature-physics\",\"isVorOnly\":false,\"title\":\"Nature Physics\"},\"publishedOn\":\"2025-09-05 04:00:00\",\"publishedOnDateReadable\":\"September 5th, 2025\"},\"versionCreatedAt\":\"2025-03-28 06:48:20\",\"video\":\"\",\"vorDoi\":\"10.1038/s41567-025-03023-3\",\"vorDoiUrl\":\"https://doi.org/10.1038/s41567-025-03023-3\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-5955283\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-5955283\",\"identity\":\"rs-5955283\",\"version\":[\"v1\"]},\"buildId\":\"XKTyCvWXoU3ODBz1xrDgd\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}