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arXiv · 2510.19709

Temperature-invariant magneto-optical Kerr effect in a noncollinear antiferromagnet

Camron Farhang·Weihang Lu·Yuchuan Yao·Pratap Pal·Shaofeng Han·Jian-Guo Zheng·Hua Chen·Chang-Beom Eom·Jing Xia
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Abstract

Noncollinear antiferromagnets exhibit anomalous Hall and magneto-optical Kerr effects driven by Berry curvature despite negligible net magnetization, promising ultrafast spintronic applications. While both effects are theoretically expected to reveal the intrinsic Berry curvature that serves as a spintronic memory bit, their quantitative interpretation is complicated by additional temperature-dependent contributions superimposed on the magnetic order parameter: extrinsic skew scattering in dc Hall transport, and optical-resonance effects in visible-wavelength Kerr measurements. Here we perform polar Kerr measurements at the infrared telecommunication wavelength (1550 nm) on epitaxial, stoichiometric Mn3NiN single crystal films, revealing for the first time a spontaneous Kerr signal that remains stable within a few percent over a 200 K range below the N\'eel temperature. This temperature-invariant intrinsic Kerr response contrasts with the strongly temperature-dependent anomalous Hall effect in the same sample dominated by extrinsic skew scattering. Our findings establish infrared Kerr effect as a robust, local probe of Berry curvature in noncollinear antiferromagnets, enabling quantitative characterization and advancing antiferromagnetic spintronic technologies.

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Camron Farhang, Weihang Lu, Yuchuan Yao, Pratap Pal, Shaofeng Han, Jian-Guo Zheng, Hua Chen, Chang-Beom Eom, Jing Xia. 2025-10-22. Temperature-invariant magneto-optical Kerr effect in a noncollinear antiferromagnet. https://doi.org/10.1103/wmh3-qf3k

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