Influence of transition-metal composition on anomalous Nernst effect in amorphous Tb–Fe–Co thin films

Abstract

We conducted a comprehensive study on the transition-metal compositional dependence of the anomalous Nernst effect (ANE) in amorphous (amo.) Tb–Fe–Co thin films. The anomalous Nernst coefficient strongly depends not only on the Tb composition but also on the transition metal composition, reaching a maximum of 1.8 μV/K for amo. Tb11.0(Fe50.0Co50.0)89.0. By evaluating the electrical and thermoelectric properties, it was clarified that this maximum is achieved by the superposition of two large contributions: S1 arising from direct transverse electron conduction due to a temperature gradient and S2 resulting from the combined Seebeck and anomalous Hall effects. By examining the transition-metal composition dependence in detail, we discovered that, despite being amorphous structures, the 3d electrons of the transition metal could be sensitively contributing to the ANE and anomalous Hall effect as if they were electron-doped. Our research provides insights for enhancing the ANE in amorphous structures.