Anomalous Nernst and Seebeck coefficients in epitaxial thin film Co2MnAlxSi1 −x and Co2FeAl

We have measured the Seebeck and anomalous Nernst coefficients and corresponding transverse and longitudinal thermoelectric conductivities from 2 to 400 K in thin film (thickness t ∼10 nm) Co₂MnAl_xSi_{1 −x} (0 ≤x ≤1 ) and Co₂FeAl grown by molecular beam epitaxy (MBE). A large (−14 A m⁻¹K⁻¹ at 300 K) anomalous component of the transverse thermoelectric conductivity is observed in Co₂MnAl , especially as contrasted to Co₂MnSi (0.28 A m⁻¹K⁻¹ at 300 K). This enhancement is likely due to Weyl points close to the Fermi level of Co₂MnAl which disappear as x decreases.