Observation of Anomalous Hall Effect in Collinear Antiferromagnet IrMn.

Zhu, Daoqian; Lu, Jiaqi; Jiang, Yuhao; Zheng, Zhenyi; Wang, Di; Zhou, Chenghang; Zhou, Jing; Chen, Shaohai et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

The anomalous Hall effect (AHE) is a transport phenomenon typically observed in ferromagnetic materials with broken time-reversal symmetry <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>T</mi></math>. Recently, the AHE has been observed in several archetype antiferromagnets (AFMs), including altermagnets, and AFMs with noncollinear, noncoplanar or canted Néel order, due to the breaking of joint symmetry of sublattice-transposing and time-reversal operation. However, the AHE is generally not allowed in collinear AFMs due to symmetry constraints. Here, we report the observation of the AHE in a collinear AFM L1<sub>0</sub>-IrMn (001) film. Scanning transmission electron microscopy investigation shows the presence of (200)-oriented grains in the L1<sub>0</sub>-IrMn (001)-oriented film due to the large lattice mismatch between the films and substrate. Consequently, the <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>t</mi></mrow><mrow><mrow><mn>1</mn></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></msub><mi>T</mi></math> joint symmetry, with <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>t</mi></mrow><mrow><mrow><mn>1</mn></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></msub></math> being the translation operation, may be locally broken in our samples, thus enabling the AHE, which is further supported by ab initio calculations. Our work provides a novel way to generate the AHE in AFMs by engineering the local symmetry.