Largely Suppressed Magneto-Thermal Conductivity and Enhanced Magneto-Thermoelectric Properties in PtSn4.

Chenguang Fu,Abhay K Srivastava,Walter Schnelle,Johannes Gooth,Guowei Li,Sarah J Watzman,Yan Sun,Stuart S P Parkin,Claudia Felser,Rana Saha,Satya N Guin,Thomas Scaffidi

doi:10.34133/2020/4643507

Abstract

Highly conductive topological semimetals with exotic electronic structures offer fertile ground for the investigation of the electrical and thermal transport behavior of quasiparticles. Here, we find that the layer-structured Dirac semimetal PtSn4 exhibits a largely suppressed thermal conductivity under a magnetic field. At low temperatures, a dramatic decrease in the thermal conductivity of PtSn4 by more than two orders of magnitude is obtained at 9 T. Moreover, PtSn4 shows both strong longitudinal and transverse thermoelectric responses under a magnetic field. Large power factor and Nernst power factor of approximately 80–100 μW·cm−1·K−2 are obtained around 15 K in various magnetic fields. As a result, the thermoelectric figure of merit zT is strongly enhanced by more than 30 times, compared to that without a magnetic field. This work provides a paradigm for the decoupling of the electron and hole transport behavior of highly conductive topological semimetals and is helpful for developing topological semimetals for thermoelectric energy conversion.

Highlights

In recent years, thermoelectric effects have attracted considerable attention in the fields of materials science and solid-state physics and chemistry
Large magneto-thermopower and Nernst thermopower were observed in both single crystals and polycrystalline samples [10, 16, 26]. These findings demonstrate that topological semimetals provide fertile ground for exploring magneticfield-mediated thermoelectric properties
We study the electrical and thermal transport properties of the Dirac semimetal PtSn4 under a magnetic field

Summary

Introduction

Thermoelectric effects have attracted considerable attention in the fields of materials science and solid-state physics and chemistry. Investigations of thermoelectric phenomena are important for understanding the fundamental transport behavior of quasiparticles in solid materials [2]. The thermoelectric efficiency of a material is gauged by the figure of merit, zT = S2T/ρκ, where S, T, ρ, and κ are the thermopower, absolute temperature, electrical resistivity, and thermal conductivity, respectively. Metals or semimetals, owing to strong coupling of S, ρ, and the electronic thermal conductivity κe, have attracted much less attention for thermoelectric studies. The key to developing metals or semimetals for thermoelectric application lies in the decoupling of the three electrical transport parameters

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