Exchange-biased topological transverse thermoelectric effects in a Kagome ferrimagnet

Heda Zhang,Milos Sretenovic,Chunqiang Xu,Xianglin Ke,Jahyun Koo,Binghai Yan

doi:10.1038/s41467-022-28733-7

Abstract

Kagome metal TbMn6Sn6 was recently discovered to be a ferrimagnetic topological Dirac material by scanning tunneling microscopy/spectroscopy measurements. Here, we report the observation of large anomalous Nernst effect and anomalous thermal Hall effect in this compound. The anomalous transverse transport is consistent with the Berry curvature contribution from the massive Dirac gaps in the 3D momentum space as demonstrated by our first-principles calculations. Furthermore, the transverse thermoelectric transport exhibits asymmetry with respect to the applied magnetic field, i.e., an exchange-bias behavior. Together, these features place TbMn6Sn6 as a promising system for the outstanding thermoelectric performance based on anomalous Nernst effect.

Highlights

Kagome metal TbMn6Sn6 was recently discovered to be a ferrimagnetic topological Dirac material by scanning tunneling microscopy/spectroscopy measurements
Most of the previous studies of magnetic topological materials have been focused on the non-trivial band topology, the corresponding surface states, and the intrinsic anomalous Hall effect (AHE)[19]
In addition to AHE, we show that TbMn6Sn6 exhibits both large anomalous Nernst effect (ANE) (2.2 μV/K at 300 K) and anomalous thermal Hall effect (ATHE, 0.12 W/mK at 300 K)

Summary

Introduction

Kagome metal TbMn6Sn6 was recently discovered to be a ferrimagnetic topological Dirac material by scanning tunneling microscopy/spectroscopy measurements. The transverse thermoelectric transport exhibits asymmetry with respect to the applied magnetic field, i.e., an exchange-bias behavior. Together, these features place TbMn6Sn6 as a promising system for the outstanding thermoelectric performance based on anomalous Nernst effect. From the viewpoint of technological applications, the ANE-based design allows for building malleable thermoelectric modules by patterning the thermopile onto flexible substrates[22–28] This is illustrated by the schematic shown, where magnetic topological materials with alternating magnetization are patterned next to each other and electrically connected in series, which can lead to a large thermoelectric voltage output. Our first-principles calculations demonstrate that the large Berry curvature of the massive Dirac gaps in the 3D momentum space leads to the intrinsic anomalous transverse conductivities. This study highlights the potential of utilizing this magnetic topological material as a thermoelectric module

Methods

Results

Conclusion