Source capture, zotero
Authors Yi-Ming Wu, Tobias Helbig, Salahudin V. Smailagić, Hao-Xin Wang, Yijun Yu, Harold Y. Hwang, Srinivas Raghu
arXiv / Publisher https://arxiv.org/abs/2602.20288
PDF https://arxiv.org/pdf/2602.20288
Relevance score 5.185
Primary category cond-mat.supr-con
Published 2026-02-27
Research paradigm Theoretical
Sample form Unknown

Summary

This study investigates the superconductivity and magnetism of bilayer nickelates from an itinerant perspective. Based on tight-binding fitting of angle-resolved photoemission spectroscopy data from compressively strained films, the authors introduced standard on-site repulsive interactions (including intra-orbital U, inter-orbital U′, Hund’s coupling JH, and pair-hopping JP) and renormalized these bare interactions through the random phase approximation (RPA) by considering particle-hole fluctuations, thereby obtaining an effective pairing interaction. The results show that in the strong Hund’s coupling regime, s-wave superconductivity and (π/2, π/2) spin density wave (SDW) order are the dominant ground states, while under weak Hund’s coupling, d-wave pairing and (π, π) SDW become the leading ground states. These findings are qualitatively consistent with previous density matrix renormalization group (DMRG) studies, underscoring the critical role of Hund’s coupling in determining the superconducting pairing symmetry and magnetic type of the system.

Materials

Methods

Keywords

Highlights

  • Key role of Hund's coupling in determining nature of superconductivity and magnetism.
  • Qualitative consistency with DMRG studies.

Conclusions

  • In strong Hund's coupling regime, s-wave superconductivity and (π/2,π/2) SDW order are favored; in weak Hund's coupling, d-wave pairing and (π,π) SDW are leading.

Main claims

  • Strong Hund's coupling favors s-wave superconductivity and (π/2,π/2) SDW order; weaker Hund's coupling favors d-wave pairing and (π,π) SDW
    • Evidence: From abstract: 'In the strong Hund's coupling regime, we find that s-wave superconductivity and (π/2,π/2) SDW order are the favored ground states. With weaker Hund's coupling, we find that d-wave pairing and (π,π) SDW are the leading ground states'
  • Results are qualitatively consistent with DMRG studies, highlighting key role of Hund's coupling
    • Evidence: From abstract: 'Our results are qualitatively consistent with earlier DMRG studies, and point to the key role played by Hund's coupling'

Workflow

  • model_construction — Two-orbital model with Hund's coupling captures low-energy physics
    • Materials: La3Ni2O7 compressively strained thin film
    • Methods: tight-binding fit to ARPES data
    • Observations: Fermi surface with α and β pockets
  • random_phase_approximation_calculations — Strong JH favors s-wave SC and (π/2,π/2) SDW; weak JH favors d-wave and (π,π) SDW
    • Materials: Tight-binding model
    • Methods: RPA for spin susceptibility and effective pairing interaction
    • Observations: leading pairing eigenvalue; gap symmetry; spin susceptibility
  • analysis_of_pairing_symmetry_and_magnetism — Hzund's coupling is key determinant of both pairing and magnetic order
    • Materials: RPA results
    • Methods: Linearized gap equation; Susceptibility peak analysis
    • Observations: Phase diagram of pairing symmetry; Magnetic ordering vectors