High-T C superconductivity in La3Ni2O7 based on the bilayer two-orbital t-J model

Abstract

Abstract The recently discovered high-T c superconductor La3Ni2O7 has sparked renewed interest in unconventional superconductivity. Here we study superconductivity in pressurized La3Ni2O7 based on a bilayer two-orbital t−J model, using the renormalized mean-field theory. Our results reveal a robust s ±-wave pairing driven by the inter-layer $${d}_{{z}^{2}}$$ d z 2 magnetic coupling, which exhibits a transition temperature within the same order of magnitude as the experimentally observed T c ~ 80 K. We establish a comprehensive superconducting phase diagram in the doping plane. Notably, the La3Ni2O7 under pressure is found to be situated roughly in the optimal doping regime of the phase diagram. When the $${d}_{{x}^{2}-{y}^{2}}$$ d x 2 − y 2 orbital becomes close to half-filling, d-wave and d + i s pairing can emerge from the system. We discuss the interplay between Fermi surface topology and different pairing symmetries. The stability of the s ±-wave pairing against Hund’s coupling and other magnetic exchange couplings is discussed.