Probing $k$-Space Alternating Spin Polarization via the Anomalous Hall Effect

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Hauptverfasser: Chen, Rui, Wang, Zi-Ming, Sun, Hai-Peng, Zhou, Bin, Xu, Dong-Hui
Format: Preprint
Veröffentlicht: 2025
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author Chen, Rui
Wang, Zi-Ming
Sun, Hai-Peng
Zhou, Bin
Xu, Dong-Hui
author_facet Chen, Rui
Wang, Zi-Ming
Sun, Hai-Peng
Zhou, Bin
Xu, Dong-Hui
contents Altermagnets represent a recently discovered class of collinear magnets, characterized by antiparallel neighboring magnetic moments and alternating-sign spin polarization in momentum-space($k$-space). However, experimental methods for probing the $k$-space spin polarization in altermagnets remain limited. In this work, we propose an approach to address this challenge by interfacing an altermagnet with the surface of a topological insulator. The massless Dirac fermions on the topological insulator surface acquire a mass due to the time-reversal symmetry breaking. The local $k$-space magnetic moment at the Dirac point directly determines both the sign and magnitude of this Dirac mass, resulting in an anomalous Hall effect. By measuring the Hall conductance, we can extract the local $k$-space magnetic moment. Moreover, we can map the global magnetic moment distribution by tuning the Dirac point position using an in-plane magnetic field, thereby revealing the $k$-space spin density of the altermagnet. This work establishes the Dirac fermion on the topological insulator surface as a sensitive probe for unveiling spin characters of altermagnets and those of other unconventional antiferromagnets.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14217
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Probing $k$-Space Alternating Spin Polarization via the Anomalous Hall Effect
Chen, Rui
Wang, Zi-Ming
Sun, Hai-Peng
Zhou, Bin
Xu, Dong-Hui
Mesoscale and Nanoscale Physics
Altermagnets represent a recently discovered class of collinear magnets, characterized by antiparallel neighboring magnetic moments and alternating-sign spin polarization in momentum-space($k$-space). However, experimental methods for probing the $k$-space spin polarization in altermagnets remain limited. In this work, we propose an approach to address this challenge by interfacing an altermagnet with the surface of a topological insulator. The massless Dirac fermions on the topological insulator surface acquire a mass due to the time-reversal symmetry breaking. The local $k$-space magnetic moment at the Dirac point directly determines both the sign and magnitude of this Dirac mass, resulting in an anomalous Hall effect. By measuring the Hall conductance, we can extract the local $k$-space magnetic moment. Moreover, we can map the global magnetic moment distribution by tuning the Dirac point position using an in-plane magnetic field, thereby revealing the $k$-space spin density of the altermagnet. This work establishes the Dirac fermion on the topological insulator surface as a sensitive probe for unveiling spin characters of altermagnets and those of other unconventional antiferromagnets.
title Probing $k$-Space Alternating Spin Polarization via the Anomalous Hall Effect
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2501.14217