Intrinsic anomalous Hall effect in the surface conduction regime of non-magnetic narrow-gap insulator FeSi

Abstract

The realization of an intrinsic anomalous Hall effect (AHE) in the absence of bulk magnetism is a rare phenomenon, requiring a spontaneous breaking of the time-reversal symmetry within the boundary states without a thermodynamic phase transition. Here, we report a robust, zero-field-hysteretic intrinsic AHE confined to the low-temperature surface-conduction regime of the prototypical narrow-gap insulator FeSi. By systematically investigating single crystals grown via Czochralski and chemical vapor transport methods with controlled thicknesses and surface preparations, we demonstrate that low-temperature electrical conductivity correlates with surface roughness and anti-correlates with sample thickness, confirming the emergence of surface conducting states (CSS) below T_CSS ≃ 55−75 K. Meanwhile, a robust, field-hysteretic and temperature-independent anomalous Hall conductivity is found below T_AHE≃45−70 K, implying the presence of magnetic order in the surface conduction regime. Bulk magnetic susceptibility and specific-heat measurements reveal no thermodynamic phase transitions, verifying that the sample interior remains a non-magnetic insulator. Analyses of conductivity scaling and effective three-dimensional conductivity reveal the intrinsic nature of this surface-driven AHE, evidencing the presence of an emergent magnetic order within the metallic surface of a non-magnetic bulk insulator. These findings establish FeSi as a compelling platform to investigate the interplay between strong electron correlations and anomalous Hall transport.

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Cite

BibTeX RIS

BibTeX

@misc{pan2026intrinsic,
  title = {{Intrinsic anomalous Hall effect in the surface conduction regime of non-magnetic narrow-gap insulator FeSi}},
  author = {Yong-Cheng Pan and Hwai-Chi Lin and Li-Han Wang and Chia-Nung Kuo and Han-Shiuan Lin and Che-Ning Yeh and Chin-Shan Lue and Anne de Visser and Yu-Te Hsu},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.28418},
  eprint = {2609.28418},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.28418},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Intrinsic anomalous Hall effect in the surface conduction regime of non-magnetic narrow-gap insulator FeSi
AU  - Yong-Cheng Pan
AU  - Hwai-Chi Lin
AU  - Li-Han Wang
AU  - Chia-Nung Kuo
AU  - Han-Shiuan Lin
AU  - Che-Ning Yeh
AU  - Chin-Shan Lue
AU  - Anne de Visser
AU  - Yu-Te Hsu
PY  - 2026
DA  - 2026/09/23
PB  - arXiv
DO  - 10.48550/arxiv.2609.28418
UR  - https://arxiv.org/abs/2609.28418
AB  - The realization of an intrinsic anomalous Hall effect (AHE) in the absence of bulk magnetism is a rare phenomenon, requiring a spontaneous breaking of the time-reversal symmetry within the boundary states without a thermodynamic phase transition. Here, we report a robust, zero-field-hysteretic intrinsic AHE confined to the low-temperature surface-conduction regime of the prototypical narrow-gap insulator FeSi. By systematically investigating single crystals grown via Czochralski and chemical vapor transport methods with controlled thicknesses and surface preparations, we demonstrate that low-temperature electrical conductivity correlates with surface roughness and anti-correlates with sample thickness, confirming the emergence of surface conducting states (CSS) below T_CSS ≃ 55−75 K. Meanwhile, a robust, field-hysteretic and temperature-independent anomalous Hall conductivity is found below T_AHE≃45−70 K, implying the presence of magnetic order in the surface conduction regime. Bulk magnetic susceptibility and specific-heat measurements reveal no thermodynamic phase transitions, verifying that the sample interior remains a non-magnetic insulator. Analyses of conductivity scaling and effective three-dimensional conductivity reveal the intrinsic nature of this surface-driven AHE, evidencing the presence of an emergent magnetic order within the metallic surface of a non-magnetic bulk insulator. These findings establish FeSi as a compelling platform to investigate the interplay between strong electron correlations and anomalous Hall transport.
ER  -

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