Nodal-line resonance generating the giant anomalous Hall effect of Co3Sn2S2

Schilberth, Felix and Jiang, M.-C. and Minami, S. and Kassem, M. and Mayr, F. and Koretsune, T. and Tabata, Yoshikazu and Waki, Takeshi and Nakamura, Hiroyuki and Guo, G.-Y. and Arita, Ryotaro and Kézsmárki, István and Bordács, Sándor (2023) Nodal-line resonance generating the giant anomalous Hall effect of Co3Sn2S2. PHYSICAL REVIEW B. ISSN 2469-9950

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Abstract

Giant anomalous Hall effect (AHE) and magneto-optical activity can emerge in magnets with topologically nontrivial degeneracies. However, identifying the specific band-structure features such as Weyl points, nodal lines, or planes which generate the anomalous response is a challenging issue. Since the low-energy interband transitions can govern the static AHE, we addressed this question in the prototypical magnetic Weyl semimetal Co 3 Sn 2 S 2 also hosting nodal lines by broadband polarized reflectivity and magneto-optical Kerr effect spectroscopy with a focus on the far-infrared range. In the linear dichroism spectrum we observe a strong resonance at 40 meV, which also appears in the optical Hall conductivity and primarily determines the static AHE, and thus confirms its intrinsic origin. Our material-specific theory reproduces the experimental data remarkably well and shows that strongly tilted nodal-line segments around the Fermi energy generate the resonance. While the Weyl points only give vanishing contributions, these segments of the nodal lines gapped by the spin-orbit coupling dominate the low-energy optical response and generate the giant AHE.

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