Second-harmonic voltage responce for the magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$

Abstract

We experimentally investigate longitudinal and transverse second-harmonic voltage response to ac electrical current for a magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$. In contrast to the previously observed Berry-curvature induced non-linear Hall effect for non-magnetic Weyl and Dirac semimetals, the second-harmonic transverse voltage demonstrates sophisticated interplay of different effects for Co${}_3$Sn${}_2$S${}_2$. In high magnetic fields, it is of Seebeck-like square-B law, while the low-field behavior is found to be linear and sensitive to the direction of sample magnetization. The latter can be expected both for the non-linear Hall effect and for the surface state contribution to the Seebeck effect in Weyl semimetals. Thus, thermoelectric effects are significant in Co${}_3$Sn${}_2$S${}_2$, unlike non-magnetic Weyl and Dirac materials.