Spin-Charge Conversion in an Epitaxial Kagome Flat-Band Metal
Abstract
The formation of topological flat bands near the Fermi level in kagome-structured metals has generated substantial research interest. One key consequence of this electronic structure is the strong anisotropy in charge transport, such as the significantly higher in-plane resistivity relative to the out-of-plane direction. However, the spin transport properties of these flat-band kagome metals are still largely unexplored. In this work, we investigate spin-charge conversion in CoSn, a representative flat-band kagome metal. Scanning tunneling microscopy is employed to image the CoSn surface with atomic resolution, and dI/dV spectroscopy shows clear signatures of the flat bands. Using magneto-optical techniques, we quantify the spin-orbit torque (SOT) in bilayers of ferromagnetic nickel (Ni) and c-plane CoSn thin films. We find a large effective spin Hall angle of θSH = 0.484 ± 0.005 within the CoSn layers, significantly exceeding the value measured for Pt of θSH = 0.0436 ± 0.0003 in Ni/Pt bilayers. Density functional theory (DFT) calculations provide a microscopic understanding of the intrinsic spin Hall effect in CoSn, elucidating the sources of Berry curvature in momentum space. These findings establish kagome metals as promising materials for efficient spin-charge conversion and low-power spintronics.
Related
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BibTeX
@misc{zhou2026spincharge,
title = {{Spin-Charge Conversion in an Epitaxial Kagome Flat-Band Metal}},
author = {Wenyi Zhou and Yuqing Zhu and Katherine Johnson and Hari Paudyal and Duy Nguyen and Dimitri King and Jaden Ma and Jay A. Gupta and Michael E. Flatte and Roland K. Kawakami},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36501},
eprint = {2610.36501},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36501},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Spin-Charge Conversion in an Epitaxial Kagome Flat-Band Metal
AU - Wenyi Zhou
AU - Yuqing Zhu
AU - Katherine Johnson
AU - Hari Paudyal
AU - Duy Nguyen
AU - Dimitri King
AU - Jaden Ma
AU - Jay A. Gupta
AU - Michael E. Flatte
AU - Roland K. Kawakami
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.36501
UR - https://arxiv.org/abs/2610.36501
AB - The formation of topological flat bands near the Fermi level in kagome-structured metals has generated substantial research interest. One key consequence of this electronic structure is the strong anisotropy in charge transport, such as the significantly higher in-plane resistivity relative to the out-of-plane direction. However, the spin transport properties of these flat-band kagome metals are still largely unexplored. In this work, we investigate spin-charge conversion in CoSn, a representative flat-band kagome metal. Scanning tunneling microscopy is employed to image the CoSn surface with atomic resolution, and dI/dV spectroscopy shows clear signatures of the flat bands. Using magneto-optical techniques, we quantify the spin-orbit torque (SOT) in bilayers of ferromagnetic nickel (Ni) and c-plane CoSn thin films. We find a large effective spin Hall angle of θ_SH = 0.484 ± 0.005 within the CoSn layers, significantly exceeding the value measured for Pt of θ_SH = 0.0436 ± 0.0003 in Ni/Pt bilayers. Density functional theory (DFT) calculations provide a microscopic understanding of the intrinsic spin Hall effect in CoSn, elucidating the sources of Berry curvature in momentum space. These findings establish kagome metals as promising materials for efficient spin-charge conversion and low-power spintronics.
ER -