Enhanced superconductivity via layer differentiation in trilayer Hubbard model

Abstract: Motivated by the highest superconducting transition temperature ($T_c$) in multilayer cuprates,we investigated the trilayer Hubbard model by adopting the large-scale dynamical cluster quantum Monte Carlo simulations. Focusing on the systems with higher hole dopings within the two outer layers (OL) than the inner layer (IL), which is believed to be relevant to the realistic multilayer cuprates, our exploration discovered that the IL and OL manifest strong differentiation in a wide range of hole doping combinations. Specifically, the OLs remain metallic while the IL shows a distinct transition from the pseudogap to superconducting state. More importantly, the highest $T_c$ of the composite trilayer system can be largely enhanced compared to the single layer model and the imbalanced hole dopings between IL and OL is beneficial to the global SC. We further provide strong numerical evidence on the picture that the IL itself can drive the $d$-wave superconductivity while the OLs only serve as the charge reservoir. Our investigation provides new insight into the origin of highest $T_c$ in multilayer cuprates.