Experimental Evidence of Néel-Order-Driven Magneto-optical Kerr Effect in an Altermagnetic Insulator

Haolin Pan; Rui-Chun Xiao; Jiahao Han; Hongxing Zhu; Junxue Li; Qian Niu; Yang Gao; Dazhi Hou

doi:10.1103/q8ym-l2zt

Experimental Evidence of Néel-Order-Driven Magneto-optical Kerr Effect in an Altermagnetic Insulator

Haolin Pan¹, Rui-Chun Xiao^2,3, Jiahao Han⁴, Hongxing Zhu ⁵, Junxue Li⁵, Qian Niu^6,7, Yang Gao^1,6,7,8, and Dazhi Hou ^1,7,*

¹International Center for Quantum Design of Functional Materials, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
²Institute of Physical Science and Information Technology, Anhui University, Hefei 230601, China
³Anhui Provincial Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei 230601, China
⁴Center for Science and Innovation in Spintronics, Tohoku University, Sendai 980-8577, Japan
⁵Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
⁶CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
⁷Department of Physics, University of Science and Technology of China, Hefei 230026, China
⁸Anhui Center for Fundamental Sciences in Theoretical Physics, University of Science and Technology of China, Hefei 230026, China

^*Contact author: dazhi@ustc.edu.cn

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Phys. Rev. Lett. 136, 036701 – Published 23 January, 2026

DOI: https://doi.org/10.1103/q8ym-l2zt

Abstract

The magneto-optical Kerr effect (MOKE) is investigated in hematite, a collinear antiferromagnetic insulator, across a broad wavelength spectrum. By combining the optical measurements with magnetometry results, we unambiguously demonstrate that the Néel-order contribution dominates the MOKE signal, while contributions from net magnetization and external magnetic fields are negligible. This conclusion is quantitatively supported by first-principles calculations, and qualitatively by a symmetry analysis that the Néel contribution appears at the first order in spin-orbit coupling while the magnetization contribution starts only at the third order. This study clarifies the altermagnetic origin of the pronounced MOKE in hematite, underscoring the potential of altermagnets as a promising new class of magneto-optical materials.

Physical Review Letters

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Experimental Evidence of Néel-Order-Driven Magneto-optical Kerr Effect in an Altermagnetic Insulator

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Experimental Evidence of Néel-Order-Driven Magneto-optical Kerr Effect in an Altermagnetic Insulator

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