Giant spontaneous Kerr effect reveals the defect origin of macroscopic time-reversal symmetry breaking in altermagnetic MnTe

Fuente: arXiv
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Main Authors: Yang, Weitung, Won, Choongjae, Cress, Cory, Franklin, Marshall Zachary, Fang, Xiaochen, Fields, Shelby, Combs, Nicholas, Han, Shaofeng, Lu, Weihang, Bennett, Steven P., Cheong, Sang-Wook, Xia, Jing
Format: Preprint
Published: 2026
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author Yang, Weitung
Won, Choongjae
Cress, Cory
Franklin, Marshall Zachary
Fang, Xiaochen
Fields, Shelby
Combs, Nicholas
Han, Shaofeng
Lu, Weihang
Bennett, Steven P.
Cheong, Sang-Wook
Xia, Jing
author_facet Yang, Weitung
Won, Choongjae
Cress, Cory
Franklin, Marshall Zachary
Fang, Xiaochen
Fields, Shelby
Combs, Nicholas
Han, Shaofeng
Lu, Weihang
Bennett, Steven P.
Cheong, Sang-Wook
Xia, Jing
contents Altermagnetism, a recently identified third class of collinear magnetism with spin-split bands and vanishing net magnetization, has emerged in hexagonal \alphaMnTe{} and is regarded as a promising platform for ultrafast, stray-field-free spintronics and for optical readout of spin order at telecommunication wavelengths. Whether the macroscopic symmetry-breaking signatures reported in MnTe, a spontaneous Hall effect and a tiny ``gossamer'' remanent moment, reflect the ideal altermagnetic order or are activated by defects remains an open question. Here we report giant spontaneous Kerr rotations of up to $\pm 1500\microrad$ in \alphaMnTe{} single crystals at the telecommunication wavelength of $1550\,\mathrm{nm}$, onsetting precisely at the Néel temperature $\TN = 307\,\mathrm{K}$. In contrast, a stoichiometric insulating \alphaMnTe{} thin film shows no detectable signal. The bulk--film contrast identifies carrier self-doping, rather than the ideal altermagnetic order, as the source of macroscopic magneto-optical response, establishing telecom-wavelength Kerr imaging as a practical readout for altermagnetic spintronics.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21021
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Giant spontaneous Kerr effect reveals the defect origin of macroscopic time-reversal symmetry breaking in altermagnetic MnTe
Yang, Weitung
Won, Choongjae
Cress, Cory
Franklin, Marshall Zachary
Fang, Xiaochen
Fields, Shelby
Combs, Nicholas
Han, Shaofeng
Lu, Weihang
Bennett, Steven P.
Cheong, Sang-Wook
Xia, Jing
Strongly Correlated Electrons
Materials Science
Optics
Altermagnetism, a recently identified third class of collinear magnetism with spin-split bands and vanishing net magnetization, has emerged in hexagonal \alphaMnTe{} and is regarded as a promising platform for ultrafast, stray-field-free spintronics and for optical readout of spin order at telecommunication wavelengths. Whether the macroscopic symmetry-breaking signatures reported in MnTe, a spontaneous Hall effect and a tiny ``gossamer'' remanent moment, reflect the ideal altermagnetic order or are activated by defects remains an open question. Here we report giant spontaneous Kerr rotations of up to $\pm 1500\microrad$ in \alphaMnTe{} single crystals at the telecommunication wavelength of $1550\,\mathrm{nm}$, onsetting precisely at the Néel temperature $\TN = 307\,\mathrm{K}$. In contrast, a stoichiometric insulating \alphaMnTe{} thin film shows no detectable signal. The bulk--film contrast identifies carrier self-doping, rather than the ideal altermagnetic order, as the source of macroscopic magneto-optical response, establishing telecom-wavelength Kerr imaging as a practical readout for altermagnetic spintronics.
title Giant spontaneous Kerr effect reveals the defect origin of macroscopic time-reversal symmetry breaking in altermagnetic MnTe
topic Strongly Correlated Electrons
Materials Science
Optics
url https://arxiv.org/abs/2604.21021