Thickness dependence of the anomalous Nernst effect and the Mott relation of Weyl semimetal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Co</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>MnGa</mml:mi></mml:mrow></mml:math> thin films
Gyu Hyeon Park, Helena Reichlová, Richard Schlitz, Michaela Lammel, Αναστάσιος Μάρκου, Peter Swekis, Philipp Ritzinger, Dominik Kriegner, Jonathan Noky, Jacob Gayles, Yan Sun, Claudia Felser, Kornelius Nielsch, Sebastian T. B. Goennenwein, Andy Thomas
Abstract
We report a robust anomalous Nernst effect in ${\mathrm{Co}}_{2}\mathrm{MnGa}$ thin films in the thickness regime between 20 and 50 nm. The anomalous Nernst coefficient varied in the range of \ensuremath{-}2.0 to \ensuremath{-}3.0 $\ensuremath{\mu}\mathrm{V}/\mathrm{K}$ at 300 K. We demonstrate that the anomalous Hall and Nernst coefficients exhibit similar behavior and fulfill the Mott relation. We simultaneously measure all four transport coefficients of the longitudinal resistivity, transversal resistivity, Seebeck coefficient, and anomalous Nernst coefficient. We connect the values of the measured and calculated Nernst conductivity by using the remaining three magnetothermal transport coefficients, where the Mott relation is still valid. The intrinsic Berry curvature dominates the transport due to the relation between the longitudinal and transversal transport. Therefore, we conclude that the Mott relationship is applicable to describe the magnetothermoelectric transport in Weyl semimetal ${\mathrm{Co}}_{2}\mathrm{MnGa}$ as a function of film thickness.