Significant Unconventional Anomalous Hall Effect in Heavy Metal/Antiferromagnetic Insulator Heterostructures

TL;DR

This study reveals an unconventional high-temperature anomalous Hall effect in heavy metal/antiferromagnetic insulator heterostructures, driven by noncollinear AFM spin textures stabilized by interfacial interactions and thermal effects.

Contribution

It uncovers a novel high-temperature AHE mechanism linked to noncollinear AFM spin textures near the Ne9el temperature, supported by atomistic spin dynamics simulations.

Findings

High anomalous Hall resistivity observed near Ne9el temperature

Unconventional AHE persists at high temperatures, vanishing at low temperatures

Spin textures stabilized by interfacial interactions and thermal fluctuations

Abstract

The anomalous Hall effect (AHE) is a quantum coherent transport phenomenon that conventionally vanishes at elevated temperatures because of thermal dephasing. Therefore, it is puzzling that the AHE can survive in heavy metal (HM)/antiferromagnetic (AFM) insulator (AFMI) heterostructures at high temperatures yet disappears at low temperatures. In this paper, we report that an unconventional high-temperature AHE in HM/AFMI is observed only around the N\'eel temperature of AFM, with large anomalous Hall resistivity up to 40 n$\Omega$ cm. This mechanism is attributed to the emergence of a noncollinear AFM spin texture with a non-zero net topological charge. Atomistic spin dynamics simulation shows that such a unique spin texture can be stabilized by the subtle interplay among the collinear AFM exchange coupling, interfacial Dyzaloshinski-Moriya interaction, thermal fluctuation, and bias magnetic field.