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arXiv · 2401.14734

Chiral electronic excitations and strong electron-phonon coupling to Weyl fermions in the Kagome semimetal Co$_3$Sn$_2$S$_2$

G. He·M. Kute·Z. C. Xu·L. Peis·R. Stumberger·A. Baum·D. Jost·E. M. Been·B. Moritz·J. Shen·Y. G. Shi·T. P. Devereaux·R. Hackl
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Abstract

We present results of a Raman scattering study of the Kagome ferromagnet Co$_3$Sn$_2$S$_2$, with a focus on electronic and phononic excitations and their interplay. We provide a theoretical analysis of the electronic band structure, enabling a semi-quantitative explanation of the spectra. A prominent feature in the electronic spectra is a redistribution of spectral weight from low to high energies in all polarization configurations starting at the Curie temperature T$_C$. In the symmetry-resolved spectra, the suppression of the A$_{1g}$ continuum in the ferromagnetic state arises from the redistribution of electronic states below T$_C$, while a strong enhancement of the A$_{2g}$ continuum is linked to the dynamics of fermions near the Fermi level $E_{\rm F}$ being characterized by spin-momentum locking near Weyl points. The A$_{1g}$ phonon modulates the position of these Weyl points and couples strongly to the related fermions close to $E_{\rm F}$. These results allow a comprehensive understanding of the bulk band structure evolution as a function of temperature in Co$_3$Sn$_2$S$_2$, offering key insights for further studies of the driving force behind the long-range magnetic order and novel topological states in this compound.

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G. He, M. Kute, Z. C. Xu, L. Peis, R. Stumberger, A. Baum, D. Jost, E. M. Been, B. Moritz, J. Shen, Y. G. Shi, T. P. Devereaux, R. Hackl. 2024-01-26. Chiral electronic excitations and strong electron-phonon coupling to Weyl fermions in the Kagome semimetal Co$_3$Sn$_2$S$_2$. https://doi.org/10.1103/wkzr-vfgn

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