paper

Large anomalous Nernst effect in thin films of the Weyl semimetal Co2MnGa

arXiv:1807.06487 · doi:10.1063/1.5048690

Abstract

The magneto-thermoelectric properties of Heusler compound thin films are very diverse. Here, we discuss the anomalous Nernst response of Co $_{2}$ MnGa thin films. We systematically study the anomalous Nernst coefficient as a function of temperature, and we show that unlike the anomalous Hall effect, the anomalous Nernst effect in Co $_{2}$ MnGa strongly varies with temperature. We exploit the on-chip thermometry technique to quantify the thermal gradient, which enables us to directly evaluate the anomalous Nernst coefficient. We compare these results to a reference CoFeB thin film. We show that the 50-nm-thick Co $_{2}$ MnGa films exhibit a large anomalous Nernst effect of -2 $I^¼$ V/K at 300 K, whereas the 10-nm-thick Co $_{2}$ MnGa film exhibits a significantly smaller anomalous Nernst coefficient despite having similar volume magnetizations. These findings suggest that the microscopic origin of the anomalous Nernst effect in Co $_{2}$ MnGa is complex and may contain contributions from skew-scattering, side-jump or intrinsic Berry phase. In any case, the large anomalous Nernst coefficent of Co $_{2}$ MnGa thin films at room temperature makes this material system a very promising candidate for efficient spin-caloritronic devices.