Yi-Zhuang You - Superconductivity from Doping La3Ni2O7 Symmetric Mass Insulators @ UCSD 11/29/2023

Yi-Zhuang You (UCSD)

Superconductivity from Doping Symmetric Mass Generation Insulators: Application to La3Ni2O7 under Pressure

@UCSD 11/29/2023

We investigate the bilayer nickelates as a platform to realize the symmetric mass generation (SMG) insulator, a featureless Mott insulator that arises due to the Lieb-Schultz-Mattis (LSM) anomaly cancellation in bilayer spin-1/2 lattice systems. Through a single-orbital bilayer square lattice model involving intralayer hopping t and interlayer superexchange interaction J, we demonstrate the emergence of high-temperature superconductivity (SC) upon doping the SMG insulator. The SC phase features s-wave interlayer spin-singlet pairing and exhibits a crossover between the BCS and BEC limits by tuning the J/t ratio. We estimate the SC transition temperature Tc from both the weak and strong coupling limits at the mean-field level. Our findings offer insights into the experimentally observed decrease in Tc with pressure and the strange metal behavior above Tc. Additionally, we propose that both Ni 3dz2 and 3dx2−y2 orbitals can exhibit superconductivity in La3Ni2O7 under pressure, but their Tc should vary in opposite ways under doping. This characteristic difference suggests a potential experimental pathway to identify which electronic orbital plays the principal role in the formation of superconductivity in this system.

https://arxiv.org/abs/2308.11195