Large magneto-optical Kerr effect induced by collinear antiferromagnetic order
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866909995632689152 |
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| author | Yoshimochi, H. Yoshida, K. Oiwa, R. Nomoto, T. Khanh, N. D. Kitaori, A. Takagi, R. Arita, R. Seki, S. |
| author_facet | Yoshimochi, H. Yoshida, K. Oiwa, R. Nomoto, T. Khanh, N. D. Kitaori, A. Takagi, R. Arita, R. Seki, S. |
| contents | In modern technology, the optical readout of magnetic information is conventionally achieved by the magneto-optical Kerr effect, i.e., the polarization rotation of reflected light. The Kerr rotation is sensitive to time-reversal symmetry breaking and generally proportional to magnetization, enabling optical readout of the up and down spin states in ferromagnets. By contrast, antiferromagnets with a collinear antiparallel spin arrangement have long been considered inactive to such magneto-optical responses, because of Tt-symmetry (time-reversal T followed by translation t symmetry) and lack of macroscopic magnetization. Here, we report the observation of giant magneto-optical Kerr effect in a room-temperature antiferromagnetic insulator alpha-Fe2O3. In this compound, the up-down and down-up spin states induce the opposite sign of spontaneous Kerr effect, whose Kerr rotation angle turned out to be exceptionally large (~ 80 mdeg, comparable to typical ferromagnets). Our first-principles calculations successfully reproduce both the absolute magnitude and spectral shape of the Kerr rotation and ellipticity with remarkable accuracy, which unambiguously proves that it originates from a Tt-symmetry-broken collinear antiferromagnetic order, rather than magnetization. This compound hosts temperature-dependent transition between easy-plane and easy-axis antiferromagnetic states, and their contrasting behaviors are also investigated in detail. The present results demonstrate that even a simple collinear antiferromagnetic order can induce a giant magneto-optical Kerr effect, and highlight Tt-symmetry-broken antiferromagnets as a promising material platform for highly sensitive optical detection of up-down and down-up spin states. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_13723 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Large magneto-optical Kerr effect induced by collinear antiferromagnetic order Yoshimochi, H. Yoshida, K. Oiwa, R. Nomoto, T. Khanh, N. D. Kitaori, A. Takagi, R. Arita, R. Seki, S. Strongly Correlated Electrons Materials Science In modern technology, the optical readout of magnetic information is conventionally achieved by the magneto-optical Kerr effect, i.e., the polarization rotation of reflected light. The Kerr rotation is sensitive to time-reversal symmetry breaking and generally proportional to magnetization, enabling optical readout of the up and down spin states in ferromagnets. By contrast, antiferromagnets with a collinear antiparallel spin arrangement have long been considered inactive to such magneto-optical responses, because of Tt-symmetry (time-reversal T followed by translation t symmetry) and lack of macroscopic magnetization. Here, we report the observation of giant magneto-optical Kerr effect in a room-temperature antiferromagnetic insulator alpha-Fe2O3. In this compound, the up-down and down-up spin states induce the opposite sign of spontaneous Kerr effect, whose Kerr rotation angle turned out to be exceptionally large (~ 80 mdeg, comparable to typical ferromagnets). Our first-principles calculations successfully reproduce both the absolute magnitude and spectral shape of the Kerr rotation and ellipticity with remarkable accuracy, which unambiguously proves that it originates from a Tt-symmetry-broken collinear antiferromagnetic order, rather than magnetization. This compound hosts temperature-dependent transition between easy-plane and easy-axis antiferromagnetic states, and their contrasting behaviors are also investigated in detail. The present results demonstrate that even a simple collinear antiferromagnetic order can induce a giant magneto-optical Kerr effect, and highlight Tt-symmetry-broken antiferromagnets as a promising material platform for highly sensitive optical detection of up-down and down-up spin states. |
| title | Large magneto-optical Kerr effect induced by collinear antiferromagnetic order |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2601.13723 |