Antiferromagnetic Chern insulators in non-centrosymmetric systems

TL;DR

This paper introduces a new class of antiferromagnetic Chern insulators in non-centrosymmetric 2D systems, demonstrating their topological properties and potential for realizing quantum anomalous Hall effects.

Contribution

It reveals the existence of AF Chern insulators driven by interactions without net magnetization, and analyzes their phase structure in a honeycomb lattice model.

Findings

Identification of a $C=1$ AFCI phase in the honeycomb model

Discovery of a spin-flop transition to a trivial antiferromagnetic phase

Proposal of experimental platforms for AFCI and QAHE

Abstract

We investigate a new class of topological antiferromagnetic (AF) Chern insulators driven by electronic interactions in two-dimensional systems without inversion symmetry. Despite the absence of a net magnetization, AF Chern insulators (AFCI) possess a nonzero Chern number $C$ and exhibit the quantum anomalous Hall effect (QAHE). Their existence is guaranteed by the bifurcation of the boundary line of Weyl points between a quantum spin Hall insulator and a topologically trivial phase with the emergence of AF long-range order. As a concrete example, we study the phase structure of the honeycomb lattice Kane-Mele model as a function of the inversion-breaking ionic potential and the Hubbard interaction. We find an easy $z$-axis $C=1$ AFCI phase and a spin-flop transition to a topologically trivial $xy$-plane collinear antiferromagnet. We propose experimental realizations of the AFCI and QAHE in correlated electron materials and cold atom systems.