Anomalous transverse response of Co2MnGa and universality of the room-temperature αijA/σijA ratio across topological magnets

The off-diagonal (electric, thermal and thermoelectric) transport\ncoefficients of a solid can acquire an anomalous component due to the\nnon-trivial topology of the Bloch waves. We present a study of the anomalous\nHall (AHE), Nernst (ANE) and thermal Hall effects (ATHE) in the Heusler Weyl\nferromagnet Co$_2$MnGa. The Anomalous Wiedemann-Franz law, linking electric and\nthermal responses, was found to be valid over the whole temperature window.\nThis indicates that the AHE has an intrinsic origin and the Berry spectrum is\nsmooth in the immediate vicinity of the Fermi level. From the ANE data, we\nextract the magnitude and temperature dependence of $\\alpha^A_{ij}$ and put\nunder scrutiny the $\\alpha^A_{ij}/\\sigma^A_{ij}$ ratio, which approaches\nk$_B$/e at room temperature. We show that in various topological magnets the\nroom-temperature magnitude of this ratio is a sizeable fraction of k$_B$/e and\nargue that the two anomalous transverse coefficients depend on universal\nconstants, the Berry curvature averaged over a window set by either the Fermi\nwavelength (for Hall) or the de Broglie thermal length (for Nernst). Since the\nratio of the latter two is close to unity at room temperature, such a universal\nscaling finds a natural explanation in the intrinsic picture of anomalous\ntransverse coefficients.\n