Anomalous Hall Heat Current and Nernst Effect in theCuCr2Se4−xBrxFerromagnet

Abstract

In a ferromagnet, an anomalous Hall heat current, given by the off-diagonal Peltier term ${\ensuremath{\alpha}}_{xy}$, accompanies the anomalous Hall current. By combining Nernst, thermopower, and Hall experiments, we have measured how ${\ensuremath{\alpha}}_{xy}$ varies with hole density and lifetime $\ensuremath{\tau}$ in ${\mathrm{C}\mathrm{u}\mathrm{C}\mathrm{r}}_{2}{\mathrm{S}\mathrm{e}}_{4\ensuremath{-}x}{\mathrm{B}\mathrm{r}}_{x}$. At low temperatures $T$, we find that ${\ensuremath{\alpha}}_{xy}$ is independent of $\ensuremath{\tau}$, consistent with anomalous-velocity theories. Its magnitude is fixed by a microscopic geometric area $\mathcal{A}\ensuremath{\sim}34\text{ }\text{ }{\AA{}}^{2}$. Our results are incompatible with some models of the Nernst effect in ferromagnets.