Anomalous-Hall heat current and Nernst effect in the ferromagnet CuCr_2Se_{4-x}Br_x

Abstract

In a ferromagnet, an anomalous-Hall heat current, given by the off-diagonal Peltier term ${\alpha }_{xy}$, accompanies the anomalous Hall current. By combining Nernst, thermopower and Hall experiments, we have measured how ${\alpha }_{xy}$ varies with hole density and lifetime $\tau$ in $\mathrm{CuC}{\mathrm{r}}_2\mathrm{S}{\mathrm{e}}_{4-\mathrm{x}}\mathrm{B}{\mathrm{r}}_{\mathrm{x}}$. At low temperatures $T$, we find that ${\alpha }_{xy}$ is independent of $\tau$, consistent with anomalous-velocity theories. Its magnitude is fixed by a microscopic geometric area $\mathcal{A}\sim 34{\mathring{\mathrm{A}}}^2$. Our results are incompatible with some models of the Nernst effect in ferromagnets.

4 pages, 5 figures, revision with publication info