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Competing magnetic instabilities and self-doping effects in KFe2As2 under pressure

Ming-Cui Ding1,*, Gang Zhao1, Li-Ya Qiao2, and Yu-Zhong Zhang2,†

  • 1School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, People's Republic of China
  • 2School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China

  • *Contact author: mcding@ldu.edu.com
  • †Contact author: yzzhang@tongji.edu.cn
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Phys. Rev. Research 8, 013246 – Published 5 March, 2026

DOI: https://doi.org/10.1103/ypl2-vb2z

Abstract

By applying density functional theory calculations, we study the electronic and magnetic properties of KFe2As2, which exhibits two superconducting domes under pressure. We find there are competing magnetic instabilities from itinerant electrons in both superconducting phases. The lower Tc of the first superconducting phase at ambient pressure can be attributed to the competing instabilities at (π,0,π), which favor the double stripe type or plaquette antiferromagnetic order. The second superconducting phase is further suppressed by the competing ferromagnetic and stripe antiferromagnetic instabilities at higher pressure. In addition, we find that applying pressure acts as self-doping, leading to variations in instabilities from the itinerant electrons. Our results imply that the instability of the Pauli susceptibility from itinerant electrons is a possible quantity that describes the various characters of KFe2As2 under pressure and have important implications for understanding the pressure manipulation of superconductivity in iron-based superconductors.

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References (60)

  1. L. Kong, M. Papaj, H. Kim, Y. Zhang, E. Baum, H. Li, K. Watanabe, T. Taniguchi, G. Gu, P. A. Lee, and S. Nadj-Perge, Cooper-pair density modulation state in an iron-based superconductor, Nature (London) 640, 55 (2025).
  2. R. M. Fernandes, A. I. Coldea, H. Ding, I. R. Fisher, P. J. Hirschfeld, and G. Kotliar, Iron pnictides and chalcogenides: A new paradigm for superconductivity, Nature (London) 601, 35 (2022).
  3. P. Li, Y. Wang, Y. Liu, J. Yao, Z. Zhao, Z. Liu, D. Shen, H. Luo, G. Cao, and J. Jiang, D. Feng, Revealing the electron-spin fluctuation coupling by photoemission in CaKFe4As4, Phys. Rev. X 15, 021001 (2025).
  4. S. Shen, X. Zhang, H. Wo, Y. Shen, Y. Feng, A. Schneidewind, P. Čermák, W. Wang, and J. Zhao, Neutron spin resonance in the heavily hole-doped KFe2As2 superconductor, Phys. Rev. Lett. 124, 017001 (2020).
  5. Y. Peng, P. Zheng, G. Wang, R. Liu, and Z. Yin, Electronic correlation, topological properties, and spin dynamics of Fe(Se, S), Phys. Rev. B 110, 125132 (2024).
  6. D. J. Scalapino, A common thread: The pairing interaction for unconventional superconductors, Rev. Mod. Phys. 84, 1383 (2012).
  7. I. I. Mazin, M. Shimizu, N. Takemori, and H. O. Jeschke, Novel Fe-based superconductor LaFe2As2 in comparison with traditional pnictides, Phys. Rev. Lett. 123, 267001 (2019).
  8. M. Shimizu, N. Takemori, D. Guterding, and H. O. Jeschke, Importance of the Fermi surface and magnetic interactions for the superconducting dome in electron-doped FeSe intercalates, Phys. Rev. B 101, 180511(R) (2020).
  9. I. I. Mazin, D. J. Singh, M. D. Johannes, and M. H. Du, Unconventional superconductivity with a sign reversal in the order parameter of LaFeAsO1−xFx, Phys. Rev. Lett. 101, 057003 (2008).
  10. K. Kuroki, S. Onari, R. Arita, H. Usui, Y. Tanaka, H. Kontani, and H. Aoki, Unconventional pairing originating from the disconnected Fermi surfaces of superconducting LaFeAsO1−xFx, Phys. Rev. Lett. 101, 087004 (2008).
  11. R. Liu, M. Nakamura, K. Kamazawa, and X. Lu, Low-energy spin excitations in detwinned FeSe, Chin. Phys. Lett. 41, 067401 (2024).
  12. D. Guterding, S. Backes, H. O. Jeschke, and R. Valentí, Origin of the superconducting state in the collapsed tetragonal phase of KFe2As2, Phys. Rev. B 91, 140503(R) (2015).
  13. H. Wo, Q. Wang, Y. Shen, X. Zhang, Y. Hao, Y. Feng, S. Shen, Z. He, B. Pan, W. Wang et al., Coexistence of ferromagnetic and stripe-type antiferromagnetic spin fluctuations in YFe2Ge2, Phys. Rev. Lett. 122, 217003 (2019).
  14. D. J. Singh, Superconductivity and magnetism in YFe2Ge2, Phys. Rev. B 89, 024505 (2014).
  15. D. Zhao, H. L. Wo, J. Li, D. W. Song, L. X. Zheng, S. J. Li, L. P. Nie, X. G. Luo, J. Zhao, T. Wu, and X. H. Chen, Approaching itinerant magnetic quantum criticality through a Hund's coupling induced electronic crossover in the YFe2Ge2 superconductor, Phys. Rev. B 101, 064511 (2020).
  16. D. Guterding, H. O. Jeschke, I. I. Mazin, J. K. Glasbrenner, E. Bascones, and R. Valentí, Nontrivial role of interlayer cation states in iron-based superconductors, Phys. Rev. Lett. 118, 017204 (2017).
  17. P. Wiecki, B. Roy, D. C. Johnston, S. L. Bud’ko, P. C. Canfield, and Y. Furukawa, Competing magnetic fluctuations in iron pnictide superconductors: Role of ferromagnetic spin correlations revealed by NMR, Phys. Rev. Lett. 115, 137001 (2015).
  18. H. Chen, Y. Ren, Y. Qiu, W. Bao, R. H. Liu, G. Wu, T. Wu, Y. L. Xie, X. F. Wang, Q. Huang, and X. H. Chen, Coexistence of the spin-density-wave and superconductivity in the Ba1−xKxFe2As2, Europhys. Lett. 85, 17006 (2009).
  19. K. Sasmal, B. Lv, B. Lorenz, A. M. Guloy, F. Chen, Y. Y. Xue, and C. W. Chu, Superconducting Fe-based compounds (A1−xSrx)Fe2As2 with A=K and Cs with transition temperatures up to 37 K, Phys. Rev. Lett. 101, 107007 (2008).
  20. S. Avci, O. Chmaissem, D. Y. Chung, S. Rosenkranz, E. A. Goremychkin, J. P. Castellan, I. S. Todorov, J. A. Schlueter, H. Claus, A. Daoud-Aladine, D. D. Khalyavin, M. G. Kanatzidis, and R. Osborn, Phase diagram of Ba1−xKxFe2As2, Phys. Rev. B 85, 184507 (2012).
  21. D. Wu, J. Jia, J. Yang, W. Hong, Y. Shu, T. Miao, H. Yan, H. Rong, P. Ai, X. Zhang et al., Nodal s± pairing symmetry in an iron-based superconductor with only hole pockets, Nat. Phys. 20, 571 (2024).
  22. Y. Nakajima, R. Wang, T. Metz, X. Wang, L. Wang, H. Cynn, S. T. Weir, J. R. Jeffries, and J. Paglione, High-temperature superconductivity stabilized by electron-hole interband coupling in collapsed tetragonal phase of KFe2As2 under high pressure, Phys. Rev. B 91, 060508(R) (2015).
  23. J. Chen, K. Semeniuk, Z. Feng, P. Reiss, P. Brown, Y. Zou, P. W. Logg, G. I. Lampronti, and F. M. Grosche, Unconventional superconductivity in the layered iron germanide YFe2Ge2, Phys. Rev. Lett. 116, 127001 (2016).
  24. B. Wang, K. Matsubayashi, J. Cheng, T. Terashima, K. Kihou, S. Ishida, C. H. Lee, A. Iyo, H. Eisaki, and Y. Uwatoko, Absence of superconductivity in the collapsed tetragonal phase of KFe2As2 under hydrostatic pressure, Phys. Rev. B 94, 020502(R) (2016).
  25. C. Tresca and G. Profeta, Compressed tetragonal phase in XFe2As2 (X=Na, K, Rb, Cs) and in the alloy Na0.5K0.5Fe2As2, Phys. Rev. B 95, 165129 (2017).
  26. P. Wiecki, V. Taufour, D. Y. Chung, M. G. Kanatzidis, S. L. Bud'ko, P. C. Canfield, and Y. Furukawa, Pressure dependence of coherence-incoherence crossover behavior in KFe2As2 observed by resistivity and As75-NMR/NQR, Phys. Rev. B 97, 064509 (2018).
  27. A. Ptok, M. Sternik, K. J. Kapcia, and P. Piekarz, Structural, electronic, and dynamical properties of the tetragonal and collapsed tetragonal phases of KFe2As2, Phys. Rev. B 99, 134103 (2019).
  28. S. Graser, T. A. Maier, P. J. Hirschfeld, and D. J. Scalapino, Near-degeneracy of several pairing channels in multiorbital models for the Fe pnictides, New J. Phys. 11, 025016 (2009).
  29. M. C. Ding, H. Q. Lin, and Y. Z. Zhang, Hidden (π, 0) instability as an itinerant origin of bicollinear antiferromagnetism in Fe1+xTe, Phys. Rev. B 87, 125129 (2013).
  30. M. C. Ding and Y. Z. Zhang, Possible way to turn MgFeGe into an iron-based superconductor, Phys. Rev. B 89, 085120 (2014).
  31. M. C. Ding, H. Q. Lin, and Y. Z. Zhang, Distinct evolution of charge occupations on Fe 3d orbitals in hole-doped iron arsenic superconductors, Europhys. Lett. 133, 17004 (2021).
  32. J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple, Phys. Rev. Lett. 77, 3865 (1996).
  33. G. Kresse and J. Hafner, Ab initio molecular dynamics for liquid metals, Phys. Rev. B 47, 558 (1993).
  34. G. Kresse and J. Furthmüller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set, Phys. Rev. B 54, 11169 (1996).
  35. P. E. Blöchl, Projector augmented-wave method, Phys. Rev. B 50, 17953 (1994).
  36. G. Kresse and D. Joubert, From ultrasoft pseudopotentials to the projector augmented-wave method, Phys. Rev. B 59, 1758 (1999).
  37. K. Schwarz, P. Blaha, and G. K. H. Madsen, Electronic structure calculations of solids using the WIEN2k package for material sciences, Comput. Phys. Commun. 147, 71 (2002).
  38. A. A. Mostofi, J. R. Yates, Y. S. Lee, I. Souza, D. Vanderbilt, and N. Marzari, wannier90: A tool for obtaining maximally-localised Wannier functions, Comput. Phys. Commun. 178, 685 (2008).
  39. J. Kunes, R. Arita, P. Wissgott, A. Toschi, H. Ikeda, and K. Held, Wien2wannier: From linearized augmented plane waves to maximally localized Wannier functions, Comput. Phys. Commun. 181, 1888 (2010).
  40. A. Ptok, K. J. Kapcia, M. Sternik, and P. Piekarz, Superconductivity of KFe2As2 under pressure: Ab initio study of tetragonal and collapsed tetragonal phases, J. Supercond. Nov. Magn. 33, 2347 (2020).
  41. C. H. Lee, K. Kihou, H. Kawano-Furukawa, T. Saito, A. Iyo, H. Eisaki, H. Fukazawa, Y. Kohori, K. Suzuki, H. Usui, K. Kuroki, and K. Yamada, Incommensurate spin fluctuations in hole-overdoped superconductor KFe2As2, Phys. Rev. Lett. 106, 067003 (2011).
  42. P. S. Wang, P. Zhou, J. Dai, J. Zhang, X. X. Ding, H. Lin, H. H. Wen, B. Normand, R. Yu, and W. Q. Yu, Nearly critical spin and charge fluctuations in KFe2As2 observed by high-pressure NMR, Phys. Rev. B 93, 085129 (2016).
  43. Z. T. Zhang, D. Dmytriieva, S. Molatta, J. Wosnitza, S. Khim, S. Gass, A. U. B. Wolter, S. Wurmehl, H.-J. Grafe, and H. Kühne, Increasing stripe-type fluctuations in AFe2As2 (A=K, Rb, Cs) superconductors probed by As75 NMR spectroscopy, Phys. Rev. B 97, 115110 (2018).
  44. K. Zhao, J. K. Glasbrenner, H. Gretarsson, D. Schmitz, J. Bednarcik, M. Etter, J. P. Sun, R. S. Manna, A. Al-Zein, S. Lafuerza, W. Scherer, J. G. Cheng, and P. Gegenwart, Collapsed tetragonal phase as a strongly covalent and fully nonmagnetic state: Persistent magnetism with interlayer As–As bond formation in Rh-doped Ca0.8Sr0.2Fe2As2, Phys. Rev. B 97, 020510(R) (2018).
  45. Z. Y. Song, X. C. Jiang, X. F. Ouyang, and Y. Z. Zhang, Breakdown of Hund's rule for CuFeAs, Phys. Rev. B 103, 125123 (2021).
  46. A. I. Liechtenstein, V. I. Anisimov, and J. Zaanen, Density functional theory and strong interactions: Orbital ordering in Mott-Hubbard insulators, Phys. Rev. B 52, R5467 (1995).
  47. M. T. Czyzyk and G. A. Sawatzky, Local-density functional and on-site correlations: The electronic structure of La2CuO4 and LaCuO3, Phys. Rev. B 49, 14211 (1994).
  48. K. Suzuki, H. Usui, and K. Kuroki, Spin fluctuations and unconventional pairing in KFe2As2, Phys. Rev. B 84, 144514 (2011).
  49. J. P. Sun, G. Z. Ye, P. Shahi, J. Q. Yan, K. Matsuura, H. Kontani, G. M. Zhang, Q. Zhou, B. C. Sales, T. Shibauchi, Y. Uwatoko, D. J. Singh, and J. G. Cheng, High-Tc superconductivity in FeSe at high pressure: Dominant hole carriers and enhanced spin fluctuations, Phys. Rev. Lett. 118, 147004 (2017).
  50. K. Mukasa, K. Matsuura, M. Qiu, M. Saito, Y. Sugimura, K. Ishida, M. Otani, Y. Onishi, Y. Mizukami, K. Hashimoto, J. Gouchi, R. Kumai, Y. Uwatoko, and T. Shibauchi, High-pressure phase diagrams of FeSe1−xTex: Correlation between suppressed nematicity and enhanced superconductivity, Nat. Commun. 12, 381 (2021).
  51. A. Vasdev, G. Sheet, R. Chapai, T. Polakovic, V. Novosad, J. S. Jiang, A. Bhattacharya, J. F. Mitchell, D. Y. Chung, and U. Welp, Superconducting and spin-wave orders in Ba0.6K0.4Fe2As2 probed by point contact spectroscopy, Phys. Rev. B 110, 094518 (2024).
  52. M. C. Ding, B. Y. Pan, G. Zhao, and Y. Z. Zhang, Importance of the 4p states of As and the interlayer cation states in LaFe2As2 and CaFe2As2, Phys. Rev. Mater. 7, 044801 (2023).
  53. J. Z. Ma, A. van Roekeghem, P. Richard, Z. H. Liu, H. Miao, L. K. Zeng, N. Xu, M. Shi, C. Cao, et al., Correlation-induced self-doping in the iron-pnictide superconductor Ba2Ti2Fe2As4O, Phys. Rev. Lett. 113, 266407 (2014).
  54. F. Stramaglia, G. M. Pugliese, L. Tortora, L. Simonelli, C. Marini, W. Olszewski, S. Ishida, A. Iyo, H. Eisaki, T. Mizokawa, and N. L. Saini, Temperature dependence of the local structure and iron magnetic moment in the self-doped CaKFe4As4 iron-based superconductor, J. Phys. Chem. C 125, 10810 (2021).
  55. D. Lin, H. S. Xu, J. Luo, H. Huang, Y. Lu, and K. Tang, A self-doped oxygen-free high-critical-temperature (high-Tc) superconductor: SmFFeAs, Inorg. Chem. 58, 15401 (2019).
  56. A. Ghosh, S. Sen, and H. Ghosh, 1144 Fe based superconductors: Natural example of orbital selective self-doping and chemical pressure induced Lifshitz transition, Comput. Mater. Sci. 186, 109991 (2021).
  57. G. Wang, Z. Wang, and X. Shi, Self-hole-doping–induced superconductivity in KCa2Fe4As4F2, Europhys. Lett. 116, 37003 (2016).
  58. R. Zhang, P. Gao, X. Wang, and G. D. Marzi, Self-doping effect in FeSe superconductor by pressure-induced charge transfer, J. Supercond. Novel Magn. 33, 1933 (2020).
  59. K. Momma and F. Izumi, VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data, J. Appl. Crystallogr. 44, 1272 (2011).
  60. M. C. Ding, Research data for “Competing magnetic instabilities and self-doping effects in KFe2As2 under pressure” [Data set], Zenodo (2026), https://doi.org/10.5281/zenodo.18512933.

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Phys. Rev. Research 8, 013246– Published 5 March, 2026
  • Received 5 September 2025
  • Accepted 2 February 2026
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