- Physical Review Journals
All JournalsPhysics Magazine

Physical Review B

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Superconductivity in the spin-state crossover materials: Nickelates with planar-coordinated low-spin Ni2+ ions

Jiří Chaloupka1 and Giniyat Khaliullin2

PDF

Phys. Rev. B 112, 075157 – Published 28 August, 2025

DOI: https://doi.org/10.1103/s5b6-crzc

Abstract

We theoretically study quasi-two-dimensional nickel compounds, where the nickel ions assume Ni2+d8 valence state and feature a low-spin S=0 ground state quasidegenerate with S=1 ionic excitations. Such a level structure is supported by square-planar coordination of nickel ions or a suitable substitution of apical oxygens. We construct the corresponding singlet-triplet exchange model and explore its phase diagram and excitation spectrum. By hole doping, we further introduce mobile Ni3+d7 ionic configurations with effective spins S=1/2, and analyze their interactions with the d8 singlet-triplet background. The interplay with the triplet excitations in the d8 sector is found to have a deep impact on the propagation of the doped holelike charge carriers and is identified as a powerful source of Cooper pairing among them.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (33)

  1. D. Li, K. Lee, B. Y. Wang, M. Osada, S. Crossley, H. R. Lee, Y. Cui, Y. Hikita, and H. Y. Hwang, Superconductivity in an infinite-layer nickelate, Nature (London) 572, 624 (2019).
  2. H. Sun, M. Huo, X. Hu, J. Li, Z. Liu, Y. Han, L. Tang, Z. Mao, P. Yang, B. Wang, J. Cheng, D.-X. Yao, G.-M. Zhang, and M. Wang, Signatures of superconductivity near 80 K in a nickelate under high pressure, Nature (London) 621, 493 (2023).
  3. G. Wang, N. N. Wang, X. L. Shen, J. Hou, L. Ma, L. F. Shi, Z. A. Ren, Y. D. Gu, H. M. Ma, P. T. Yang, Z. Y. Liu, H. Z. Guo, J. P. Sun, G. M. Zhang, S. Calder, J.-Q. Yan, B. S. Wang, Y. Uwatoko, and J.-G. Cheng, Pressure-induced superconductivity in polycrystalline La3Ni2O7−δ, Phys. Rev. X 14, 011040 (2024).
  4. E. K. Ko, Y. Yu, Y. Liu, L. Bhatt, J. Li, V. Thampy, C.-T. Kuo, B. Y. Wang, Y. Lee, K. Lee, J.-S. Lee, B. H. Goodge, D. A. Muller, and H. Y. Hwang, Signatures of ambient pressure superconductivity in thin film La3Ni2O7, Nature (London) 638, 935 (2025).
  5. G. Zhou, W. Lv, H. Wang, Z. Nie, Y. Chen, Y. Li, H. Huang, W.-Q. Chen, Y.-J. Sun, Q.-K. Xue, and Z. Chen, Ambient-pressure superconductivity onset above 40 K in (La,Pr)3Ni2O7 films, Nature (London) 640, 641 (2025).
  6. Y. Zhu, D. Peng, E. Zhang, B. Pan, X. Chen, L. Chen, H. Ren, F. Liu, Y. Hao, N. Li, Z. Xing, F. Lan, J. Han, J. Wang, D. Jia, H. Wo, Y. Gu, Y. Gu, L. Ji, W. Wang et al., Superconductivity in pressurized trilayer La4Ni3O10−δ single crystals, Nature (London) 631, 531 (2024).
  7. M. Zhang, C. Pei, D. Peng, X. Du, W. Hu, Y. Cao, Q. Wang, J. Wu, Y. Li, H. Liu, C. Wen, J. Song, Y. Zhao, C. Li, W. Cao, S. Zhu, Q. Zhang, N. Yu, P. Cheng, L. Zhang et al., Superconductivity in trilayer nickelate La4Ni3O10 under pressure, Phys. Rev. X 15, 021005 (2025).
  8. E. Zhang, D. Peng, Y. Zhu, L. Chen, B. Cui, X. Wang, W. Wang, Q. Zeng, and J. Zhao, Bulk superconductivity in pressurized trilayer nickelate Pr4Ni3O10 single crystals, Phys. Rev. X 15, 021008 (2025).
  9. Edited by P. Gütlich and H. A. Goodwin, Spin Crossover in Transition Metal Compounds I (Springer, Berlin, 2004).
  10. V. Pardo and W. E. Pickett, Pressure-induced metal-insulator and spin-state transition in low-valence layered nickelates, Phys. Rev. B 85, 045111 (2012).
  11. R. D. Smyth, J. N. Blandy, Z. Yu, S. Liu, C. V. Topping, S. J. Cassidy, C. F. Smura, D. N. Woodruff, P. Manuel, C. L. Bull, N. P. Funnell, C. J. Ridley, J. E. McGrady, and S. J. Clarke, High- versus low-spin Ni2+ in elongated octahedral environments: Sr2NiO2Cu2Se2, Sr2NiO2Cu2S2, and Sr2NiO2Cu2(Se1−xSx)2, Chem. Mater. 34, 9503 (2022).
  12. K. Otzschi, H. Ogino, J. Shimoyama, and K. Kishio, New candidates for superconductors; a series of layered oxysulfides (Cu2S2)(Srn+1MnO3n−1), J. Low Temp. Phys. 117, 729 (1999).
  13. S. J. Clarke, P. Adamson, S. J. C. Herkelrath, O. J. Rutt, D. R. Parker, M. J. Pitcher, and C. F. Smura, Structures, physical properties, and chemistry of layered oxychalcogenides and oxypnictides, Inorg. Chem. 47, 8473 (2008).
  14. Y. Matsumoto, T. Yamamoto, K. Nakano, H. Takatsu, T. Murakami, K. Hongo, R. Maezono, H. Ogino, D. Song, C. M. Brown, C. Tassel, and H. Kageyama, High-pressure synthesis of A2NiO2Ag2Se2 (A = Sr,Ba) with a high-spin Ni2+ in square-planar coordination, Angew. Chem. Int. Ed. 58, 756 (2019).
  15. M. Matsuda, K. Katsumata, A. Zheludev, S. M. Shapiro, and G. Shirane, Neutron scattering study in BaNiO2, J. Phys. Chem. Solids 60, 1121 (1999).
  16. J. A. Alonso, M. J. Martínez-Lope, J. L. García-Muñoz, and M. T. Fernández-Díaz, A structural and magnetic study of the defect perovskite LaNiO2.5 from high-resolution neutron diffraction data, J. Phys.: Condens. Matter 9, 6417 (1997).
  17. S. Sachdev and R. N. Bhatt, Bond-operator representation of quantum spins: Mean-field theory of frustrated quantum Heisenberg antiferromagnets, Phys. Rev. B 41, 9323 (1990).
  18. S. Gopalan, T. M. Rice, and M. Sigrist, Spin ladders with spin gaps: A description of a class of cuprates, Phys. Rev. B 49, 8901 (1994).
  19. A. V. Chubukov and D. K. Morr, Phase transition, longitudinal spin fluctuations, and scaling in a two-layer antiferromagnet, Phys. Rev. B 52, 3521 (1995).
  20. T. Sommer, M. Vojta, and K. W. Becker, Magnetic properties and spin waves of bilayer magnets in a uniform field, Eur. Phys. J. B 23, 329 (2001).
  21. R. Eder, Dynamics of spin ladders, Phys. Rev. B 57, 12832 (1998).
  22. M. Vojta and K. W. Becker, Doped bilayer antiferromagnets: Hole dynamics on both sides of a magnetic ordering transition, Phys. Rev. B 60, 15201 (1999).
  23. J. Chaloupka and G. Khaliullin, Spin polaron theory for the photoemission spectra of layered cobaltates, Phys. Rev. Lett. 99, 256406 (2007).
  24. G. Khaliullin and J. Chaloupka, Origin of strong correlations and superconductivity in NaxCoO2, Phys. Rev. B 77, 104532 (2008).
  25. S. Schmitt-Rink, C. M. Varma, and A. E. Ruckenstein, Spectral function of holes in a quantum antiferromagnet, Phys. Rev. Lett. 60, 2793 (1988).
  26. C. L. Kane, P. A. Lee, and N. Read, Motion of a single hole in a quantum antiferromagnet, Phys. Rev. B 39, 6880 (1989).
  27. G. Martínez and P. Horsch, Spin polarons in the t−J model, Phys. Rev. B 44, 317 (1991).
  28. J. H. Nyhegn, K. K. Nielsen, and G. M. Bruun, Equilibrium and nonequilibrium dynamics of a hole in a bilayer antiferromagnet, Phys. Rev. B 106, 155160 (2022).
  29. P. S. Anisimov, F. Aust, G. Khaliullin, and M. Daghofer, Nontrivial triplon topology and triplon liquid in Kitaev-Heisenberg-type excitonic magnets, Phys. Rev. Lett. 122, 177201 (2019).
  30. J. Chaloupka and G. Khaliullin, Highly frustrated magnetism in relativistic d4 Mott insulators: Bosonic analog of the Kitaev honeycomb model, Phys. Rev. B 100, 224413 (2019).
  31. A. O. Sboychakov, K. I. Kugel, and A. L. Rakhmanov, Phase separation in a two-band model for strongly correlated electrons, Phys. Rev. B 76, 195113 (2007).
  32. M. Raczkowski, R. Frésard, and A. M. Oleś, Microscopic origin of diagonal stripe phases in doped nickelates, Phys. Rev. B 73, 094429 (2006).
  33. J. Chaloupka and G. Khaliullin, Zenodo (2025), https://doi.org/10.5281/zenodo.15412407.

Outline

Information

Phys. Rev. B 112, 075157– Published 28 August, 2025
  • Received 8 May 2025
  • Revised 5 August 2025
  • Accepted 13 August 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation