The recently discovered high-TC superconductor La3Ni2O7 has
sparked renewed interest in the unconventional superconductivity. Here we study
the unconventional 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
dz2 magnetic coupling, which exhibits a transition temperature within the
same order of magnitude as the experimentally observed Tc∼80 K. We
obtain a comprehensive superconducting phase diagram in the doping plane.
Notably, the La3Ni2O7 under pressure is found situated roughly in the
optimal doping regime of the phase diagram. When the dx2−y2 orbital
becomes close to half-filling, d−wave and d+is pairing can emerge from the
system. We discuss the interplay between the Fermi surface topology and
different pairing symmetries. The stability of the s±−wave pairing against
Hund's coupling and other magnetic exchange couplings is examined.Comment: 8 pages, 8 figure