High-Temperature Quantum Anomalous Hall Effect in Buckled Honeycomb Antiferromagnets

TL;DR

This paper proposes a high-temperature antiferromagnetic Chern insulator in buckled honeycomb structures, driven by electric fields and spin-orbit coupling, with potential realization in heavy transition-metal compounds.

Contribution

It introduces a mechanism for achieving high-temperature AF Chern insulators using buckled honeycomb antiferromagnets and electric fields, with predictions for room-temperature stability.

Findings

Quantized Hall conductance persists below a temperature $T_q$ dependent on spin-orbit coupling.

Spectral broadening of chiral edge states occurs above $T_q$, indicating decay.

Predicted room-temperature stability in heavy transition-metal compounds like Sr$_3$CaOs$_2$O$_9$.

Abstract

We propose N\'eel antiferromagnetic (AF) Mott insulators with a buckled honeycomb structure as potential candidates to host a high-temperature AF Chern insulator (AFCI). Using a generalized Kondo lattice model we show that the staggered potential induced by a perpendicular electric field due to the buckling can drive the AF Mott insulator to an AFCI phase. We address the temperature evolution of the Hall conductance and the chiral edge states. The quantization temperature $T_q$, below which the Hall conductance is quantized, depends essentially on the strength of the spin-orbit coupling and the hopping parameter, independent of the specific details of the model. The deviation of the Hall conductance from the quantized value $e^2/h$ above $T_q$ is found to be accompanied by a spectral broadening of the chiral edge states, reflecting a finite life-time, i.e., a decay. Using parameters typical for heavy transition-metal elements we predict that the AFCI can survive up to room temperature. We suggest Sr$_3$CaOs$_2$O$_9$ as a potential compound to realize a high-$T$ AFCI phase.