Pairing tendencies in two-orbital Hubbard models with reduced sign problem

How unconventional superconductivity arises from strong repulsive interactions is a central question in the study of high-temperature superconductivity. Here we study two-orbital Hubbard models with orbital-dependent interaction strength by large-scale Determinantal Quantum Monte Carlo (DQMC) simulations. When one orbital is strongly interacting and the other is weakly or non- interacting, the fermion sign problem is significantly reduced. Temperatures more than two orders of magnitude below the Fermi energy are accessible by DQMC. We present results for the superfluid stiffness and pairfield susceptibilities of such models and comment on their relevance to unconventional superconductors, including the recently discovered superconducting nickelates.