Doping-driven Antiferromagnetic Insulator -- Superconductor Transition: a Quantum Monte Carlo Study

TL;DR

This study uses sign-problem-free quantum Monte Carlo simulations on a bilayer Hubbard model to explore how doping transforms an antiferromagnetic insulator into a superconductor, revealing coexistence and phase transitions.

Contribution

It introduces a bilayer Hubbard model analysis with quantum Monte Carlo to detail the antiferromagnetic to superconducting transition in doped Mott insulators.

Findings

Antiferromagnetic order weakens with doping.

Superconductivity coexists with antiferromagnetism below a critical doping.

At higher doping, antiferromagnetism disappears, leaving a pure superconductor.

Abstract

How superconductivity emerges in the vicinity of an antiferromagnetic insulating state is a long-standing issue of strong correlation physics. We study the transition from an antiferromagnetic insulator to a superconductor by hole-doping based on a bilayer generalization of a Hubbard-like model. The projector quantum Monte-Carlo simulations are employed, which are sign-problem-free both at and away from half-filling. An anisotropic Ising antiferromagnetic Mott insulating phase occurs at half-filling, which is weakened by hole-doping. Below a critical doping value, antiferromagnetism coexists with the singlet superconductivity, which is a pairing across each rung with an extended $s$-wave symmetry. As further increasing doping, the antiferromagnetic order vanishes, leaving only a superconducting phase. These results provide important information on how superconductivity appears upon doping the parent Mott-insulating state.