Large longitudinal and anomalous transverse Magneto-thermoelectric effect in kagome antiferromagnet FeGe

TL;DR

This study reports a record-high transverse thermoelectric effect in Kagome antiferromagnet FeGe, driven by Berry curvature from non-collinear spins, with potential for advanced thermoelectric applications.

Contribution

It demonstrates the largest known anomalous Nernst effect in AFM Kagome materials and links it to non-collinear spin textures and Berry curvature effects.

Findings

Record transverse thermoelectric conductivity of 15 A K-1m-1 in FeGe.

Significant increase in thermopower around the canted-AFM transition temperature.

Large Berry curvature from non-collinear spins enhances thermoelectric performance.

Abstract

Topological Kagome magnets, characterized by nontrivial electronic band structures featuring flat band, Dirac cone and van Hove singularities, provide a new avenue for the realization of thermoelectric devices. Unlike the conventional longitudinal Seebeck effect, transverse thermoelectric (TE) effects like the Nernst effect have attracted growing interest due to their unique transverse geometry and potential advantages. Here, we report the observation of a significant transverse thermoelectric conductivity alpha A_zx of 15 A K-1m-1 at low temperatures, together with a pronounced anomalous Nernst effect in the Kagome antiferromagnet FeGe, which exhibits a charge density wave inside the antiferromagnetic (AFM) state. This value is the highest record among known AFM materials. Furthermore, the thermopower at 14 T increases by 102-104% around the canted-AFM (CAFM) transition temperature, Tcant, comparable to that of the well-known AFM thermoelectric materials. These effects are attributed to large Berry curvature arising from the non-collinear spin texture in FeGe, highlighting its potential for enhancing thermoelectric performance and its candidacy for magneto-TE applications in Kagome antiferromagnetic materials.