Negative flat band magnetism in a spin–orbit-coupled correlated kagome magnet

Jia Xin Yin, Songtian S. Zhang, Guoqing Chang, Qi Wang, Stepan S. Tsirkin, Zurab Guguchia, Biao Lian, Huibin Zhou, Kun Jiang, Ilya Belopolski, Nana Shumiya, Daniel Multer, Maksim Litskevich, Tyler A. Cochran, Hsin Lin, Ziqiang Wang, Titus Neupert, Shuang Jia, Hechang Lei, M. Zahid Hasan

Research output: Contribution to journalLetter

30 Scopus citations

Abstract

Electronic systems with flat bands are predicted to be a fertile ground for hosting emergent phenomena including unconventional magnetism and superconductivity 1–15 , but materials that manifest this feature are rare. Here, we use scanning tunnelling microscopy to elucidate the atomically resolved electronic states and their magnetic response in the kagome magnet Co 3 Sn 2 S 2 (refs. 16–20 ). We observe a pronounced peak at the Fermi level, which we identify as arising from the kinetically frustrated kagome flat band. On increasing the magnetic field up to ±8 T, this state exhibits an anomalous magnetization-polarized many-body Zeeman shift, dominated by an orbital moment that is opposite to the field direction. Such negative magnetism is induced by spin–orbit-coupling quantum phase effects 21–25 tied to non-trivial flat band systems. We image the flat band peak, resolve the associated negative magnetism and provide its connection to the Berry curvature field, showing that Co 3 Sn 2 S 2 is a rare example of a kagome magnet where the low-energy physics can be dominated by the spin–orbit-coupled flat band.

Original languageEnglish (US)
Pages (from-to)443-448
Number of pages6
JournalNature Physics
Volume15
Issue number5
DOIs
StatePublished - May 1 2019

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Yin, J. X., Zhang, S. S., Chang, G., Wang, Q., Tsirkin, S. S., Guguchia, Z., Lian, B., Zhou, H., Jiang, K., Belopolski, I., Shumiya, N., Multer, D., Litskevich, M., Cochran, T. A., Lin, H., Wang, Z., Neupert, T., Jia, S., Lei, H., & Hasan, M. Z. (2019). Negative flat band magnetism in a spin–orbit-coupled correlated kagome magnet. Nature Physics, 15(5), 443-448. https://doi.org/10.1038/s41567-019-0426-7