Magneto-optical imaging of macroscopic altermagnetic domains in MnTe

TL;DR

This study visualizes and characterizes altermagnetic domains in MnTe using magneto-optical Kerr-effect microscopy, revealing their controllability, stability, and distinct TRSB features, advancing understanding of this novel magnetic class.

Contribution

First visualization of bulk altermagnetic domains in MnTe using a simple optical technique, demonstrating their controllability and stability.

Findings

Identified two distinct TRSB domains with large Kerr rotations

Domains do not scale with tiny bulk magnetization

Domains are controllable and stable against perturbations

Abstract

Altermagnets are a new class of magnets accompanying global time-reversal symmetry breaking (TRSB) without net magnetization. The TRSB results in formation of novel altermagnetic domains. Features of altermagnetic domains, in particular their responses to external stimuli, are essentially important but yet unexplored. Here, we report visualization of bulk altermagnetic domains in MnTe based on scanning magneto-optical Kerr-effect microscopy using telecom infrared wavelength. We found two distinct TRSB domains with large Kerr rotations that do not scale with its tiny bulk magnetization. We also revealed controllability and stability of domains against magnetic or thermal perturbations. Our first observation of altermagnetic domains using a laboratory-scale simple optical technique showing their movable nature provide firm bases for future fundamental and application studies of altermagnets.