Possible high-Tc superconductivity (SC) has been found experimentally in the bilayer material La3Ni2O7 under high pressure recently, in which the Ni-3d3z2−r2 and 3dx2−y2 orbitals are expected to play a key role in the electronic structure and the SC. Here we study the two-orbital electron correlations and the nature of the SC using the bilayer two-orbital Hubbard model downfolded from the band structure of La3Ni2O7 in the framework of the dynamical mean-field theory. We find that each of the two orbitals forms s±-wave SC pairing. Because of the nonlocal inter-orbital hoppings, the two-orbital SCs are concomitant and they transition to Mott insulating states simultaneously when tuning the system to half filling. The Hund's coupling induced local inter-orbital spin coupling enhances the electron correlations pronouncedly and is crucial to the SC.
@article{arxiv.2308.09698,
title = {Correlation Effects and Concomitant Two-Orbital $s_\pm$-Wave Superconductivity in La$_3$Ni$_2$O$_7$ under High Pressure},
author = {Yi-Heng Tian and Yin Chen and Jia-Ming Wang and Rong-Qiang He and Zhong-Yi Lu},
journal= {arXiv preprint arXiv:2308.09698},
year = {2024}
}