Xuepeng Wang, Cornell University

Intertwined Orders, Spin-Polarons and Exotic Quantum Criticality in Correlated Topological Flat Bands

We consider a sign-problem-free, time-reversal symmetric model with isolated Chern bands, involving both spin and valley degrees of freedom in the presence of a class of repulsive electronic interactions. We analyze the phase diagram using a numerically exact quantum Monte Carlo (QMC) method. We find intertwined orders between a Chern antiferromagnet and a spin-singlet superconductor. The superconductivity is mediated by Cooper pairs formed from spin-polarons/skyrmions and is robust against a weak spin-orbit coupling field. We analyze the possibility of approximate emergent symmetry and exotic quantum critical points. The low-temperature phase diagram can be understood in terms of a superspin nonlinear sigma model.