Unconventional anomalous Hall effect from antiferromagnetic domain walls of Nd2Ir2O7 thin films

TL;DR

This paper demonstrates that antiferromagnetic domain walls in Nd2Ir2O7 thin films induce an unconventional anomalous Hall effect due to symmetry breaking, revealing new topological phenomena in AFM materials.

Contribution

It uncovers the emergence of a large anomalous Hall effect from AFM domain walls in Nd2Ir2O7, driven by symmetry breaking at the interfaces, a novel mechanism compared to bulk properties.

Findings

AFM domain walls break symmetry enabling AHE

Enhanced AHE observed during domain switching

DW-induced AHE linked to symmetry and topology

Abstract

Ferroic domain walls (DWs) create different symmetries and ordered states compared with those in single-domain bulk materials. In particular, the DWs of an antiferromagnet (AFM) with non-coplanar spin structure have a distinct symmetry that cannot be realized in those of their ferromagnet counterparts. In this paper, we show that an unconventional anomalous Hall effect (AHE) can arise from the DWs of a non-coplanar AFM, Nd2Ir2O7. Bulk Nd2Ir2O7 has a cubic symmetry; thus, its Hall signal should be zero without an applied magnetic field. The DWs generated in this material break the two-fold rotational symmetry, which allows for finite anomalous Hall conductivity. A strong f-d exchange interaction between the Nd and Ir magnetic moments significantly influences antiferromagnetic domain switching. Our epitaxial Nd2Ir2O7 thin film showed a large enhancement of the AHE signal when the AFM domains switched, indicating that the AHE is mainly due to DWs. Our study highlights the symmetry broken interface of AFM materials as a new means of exploring topological effects and their relevant applications.