Observation of non-volatile anomalous Nernst effect in altermagnet with collinear N\'eel vector

TL;DR

This study demonstrates the first observation of non-volatile anomalous Nernst effect in a collinear altermagnet, Mn5Si3, revealing how its unique band structure and Fermi level tuning enable efficient thermoelectric conversion.

Contribution

It provides the first experimental evidence of non-volatile ANE in collinear altermagnet Mn5Si3, highlighting the role of spin-splitting band structure and Fermi level positioning.

Findings

Non-volatile ANE observed in Mn5Si3 thin film.

Fermi level doping enhances ANE sixfold.

Neel-vector-dependent temperature scaling of ANE.

Abstract

Anomalous Nernst effect (ANE), a widely investigated transverse thermoelectric effect that converts waste heat into electrical energy with remarkable flexibility and integration capability, has been extended to antiferromagnets with non-collinear spin texture recently. ANE in compensated magnet with collinear N\'eel vector will bring more opportunities to construct magnetic-field-immune and ultrafast transverse thermoelectric converters, but remains unachieved for long. It is due to the degenerated band structure of traditional collinear compensated magnet excludes non-zero Berry curvature. Here, we realize non-volatile ANE in altermagnet Mn5Si3 thin film with collinear Neel vector, whose unique alternating spin-splitting band structure plays vital role in creating non-zero Berry curvature and hotpots of anomalous Nernst conductivity near band intersections. Interestingly, ANE is relatively weak in stoichiometric Mn5Si3, but undergoes a sixfold enhancement through strategically raising the Fermi level by additional Mn doping, indicating sensitive intrinsic influence from specific location of the Fermi level on ANE in altermagnet. Moreover, our investigation reveals a unique Neel-vector-dependent temperature-scaling relationship of anomalous Nernst conductivity in Mn5Si3. Our work not only fills a longstanding gap by confirming the presence of non-volatile ANE in collinear compensated magnet, but also enlightens thermoelectric physics related to exotic spin-splitting band structure in altermagnet.