Phase Diagram of Kane-Mele Hubbard model at small doping

TL;DR

This paper investigates the effects of Hubbard interaction on the Kane-Mele model at small doping, revealing a possible superconducting phase and its dependence on spin-orbit coupling, using density matrix renormalization group methods.

Contribution

It introduces a detailed study of interaction effects in the doped Kane-Mele model, identifying a potential superconducting phase influenced by spin-orbit coupling.

Findings

Identification of a possible superconducting phase

Strong dependence of critical interaction on SOC

Correlation functions support SC dominance

Abstract

Recent experiment on MoTe$_2$-WTe$_2$ twisted bi-layer demonstrated physics of Kane-Mele (KM) as well as Haldane models. Although topological properties of KM model has been studied extensively, effects of interaction are still less explored beyond half filling. In this work we study the effect of Hubbard interaction in KM model at small hole doping around half filling. We use density matrix renormalization group method to characterize different phase of cylinders with width of $L_y=3$ unit cells. We identify {a possible} superconducting (SC) phase and transition at different strength of spin-orbit coupling (SOC) and show the strong dependence of critical interaction for SC transition. We also calculate the single-particle Green's function, spin-spin and density-density correlations and compare with SC correlation to establish the dominance of SC correlations. Our result highlights striking behaviour of SC transition and its dependence on SOC which could be useful in understanding different ways to achieve unconventional SC.