Large anomalous Hall effect induced by weak ferromagnetism in the noncentrosymmetric antiferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">CoNb</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:math>
Hiroki Tanaka, Shota Okazaki, Kenta Kuroda, Ryo Noguchi, Yosuke Arai, Susumu Minami, S. Ideta, Kiyohisa Tanaka, Dong-Hui Lu, Makoto Hashimoto, Viktor Kandyba, Mattia Cattelan, Alexei Barinov, Takayuki Muro, T. Sasagawa, Takeshi Kondo
Abstract
We study the mechanism of the exceptionally large anomalous Hall effect (AHE) in the noncentrosymmetric antiferromagnet $\mathrm{Co}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$ by angle-resolved photoemission spectroscopy (ARPES) and magnetotransport measurements. From ARPES measurements of $\mathrm{Co}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$ and its family compounds ($\mathrm{Fe}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$ and $\mathrm{Ni}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$), we find a band dispersion unique to the Co intercalation existing near the Fermi level. We further demonstrate that a slight deficiency of sulfur in $\mathrm{Co}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$ eliminates the ferromagnetism and the AHE simultaneously while hardly changing the band structure, indicating that the weak ferromagnetism is responsible for the emergence of the large AHE. Based on our results, we propose Weyl points near the Fermi level to cause the large AHE.