Giant anomalous Nernst effect in the magnetic Weyl semimetal Co 3 Sn 2 S 2

In ferromagnetic solids, a transverse voltage can be generated by a longitudinal temperature gradient even in the absence of a magnetic field. This thermoelectric counterpart of the anomalous Hall effect is dubbed the anomalous Nernst effect (ANE), and both of these effects are expected to scale with spontaneous magnetization. Here, we report the observation of a giant ANE in a newly discovered magnetic Weyl semimetal ${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ crystal. The Hall effect and the Nernst effect show sharp jumps at a threshold field and exhibit a clear hysteresis loop below the Curie temperature ${T}_{C}$. The anomalous Nernst signal, ${S}_{yx}^{A}$, peaks at a maximum value of $\ensuremath{\sim}5$ $\ensuremath{\mu}\mathrm{V}/\mathrm{K}$, which is comparable to the largest seen in previous magnetic materials and seriously violates the conventional scale relation in conventional ferromagnets. Moreover, the anomalous transverse thermoelectric conductivity ${\ensuremath{\alpha}}_{yx}^{A}$ reaches about $\ensuremath{\sim}10$ A/K m at 70 K, the largest in known semimetals. These results together with first-principles calculation provide strong evidence that the giant ANE originated from the nontrivial Berry curvature near the chiral Weyl points, which are very close to the Fermi level in this compound.