Switchable Quantum Anomalous Hall state in a strongly frustrated lattice magnet

TL;DR

This paper demonstrates how the interaction between itinerant electrons and localized magnetic moments on a checkerboard lattice can produce switchable quantum anomalous Hall states through magnetic flux phases, with potential for controllable edge currents.

Contribution

It introduces a novel mechanism for realizing a ferromagnetic Quantum Anomalous Hall state via flux-phases in a frustrated lattice, highlighting the role of itineracy strength.

Findings

Weak itineracy yields graphene-like Dirac fermions in a coplanar flux-phase.

Stronger itineracy induces a non-coplanar, chiral flux-phase with topological mass.

The system exhibits a switchable, dissipationless edge current controlled by magnetic field.

Abstract

We establish that the interplay of itinerant fermions with localized magnetic moments on a checkerboard lattice leads to magnetic flux-phases. For weak itineracy the flux-phase is coplanar and the electronic dispersion takes the shape of graphene-like Dirac fermions. Stronger itineracy drives the formation of a non-coplanar, chiral flux-phase, in which the Dirac fermions acquire a topological mass that is proportional to a ferromagnetic spin polarization. Consequently the system self-organizes into a ferromagnetic Quantum Anomalous Hall state in which the direction of its dissipationless edge-currents can be switched by an applied magnetic field.