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arXiv · 1807.06487

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

Helena Reichlova·Richard Schlitz·Sebastian Beckert·Peter Swekis·Anastasios Markou·Yi-Cheng Chen·Savio Fabretti·Gyu Hyeon Park·Anna Niemann·Shashank Sudheendra·Andy Thomas·Kornelius Nielsch·Claudia Felser·Sebastian T. B. Goennenwein
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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$\mu$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.

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Helena Reichlova, Richard Schlitz, Sebastian Beckert, Peter Swekis, Anastasios Markou, Yi-Cheng Chen, Savio Fabretti, Gyu Hyeon Park, Anna Niemann, Shashank Sudheendra, Andy Thomas, Kornelius Nielsch, Claudia Felser, Sebastian T. B. Goennenwein. 2018-07-17. Large anomalous Nernst effect in thin films of the Weyl semimetal Co2MnGa. https://doi.org/10.1063/1.5048690

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