Anisotropic magneto-thermal transport in Co$_2$MnGa thin films

TL;DR

This study systematically investigates anisotropic magneto-transport effects in high-quality Co$_2$MnGa thin films, revealing significant thermoelectric responses and the coexistence of crystalline and non-crystalline components.

Contribution

It provides the first detailed analysis of both AMR and AMTP in Co$_2$MnGa thin films, including modeling and temperature-dependent behavior, highlighting the large AMTP due to Seebeck coefficient sign change.

Findings

Both crystalline and non-crystalline AMR components are present.

AMTP is large and changes sign with temperature.

The Seebeck coefficient's sign change explains the large thermoelectric response.

Abstract

Ferromagnetic Co$_2$MnGa has recently attracted significant attention due to effects related to non-trivial topology of its band structure, however a systematic study of canonical magneto-galvanic transport effects is missing. Focusing on high quality thin films, here we systematically measure anisotropic magnetoresistance (AMR) and its thermoelectric counterpart (AMTP). We model the AMR data by free energy minimisation within the Stoner-Wohlfarth formalism and conclude that both crystalline and non-crystalline components of this magneto-transport phenomenon are present in Co$_2$MnGa. Unlike the AMR which is small in relative terms, the AMTP is large due to a change of sign of the Seebeck coefficient as a function of temperature. This fact is discussed in the context of the Mott rule and further analysis of AMTP components is presented.