A topological transition-induced giant transverse thermoelectric effect in polycrystalline Dirac semimetal Mg3Bi2

TL;DR

This paper reports a giant transverse thermoelectric effect in Mn-doped Mg3Bi2 caused by a topological phase transition from a topological insulator to a Dirac semimetal, offering new insights for thermoelectric material design.

Contribution

It demonstrates a topological transition-induced enhancement of transverse thermoelectric properties in polycrystalline Mg3Bi2, linking topological phase changes to thermoelectric performance.

Findings

Large transverse thermopower of 617 μV/K

High power factor of 20393 μW/m·K²

Significant magnetoresistance of 16600%

Abstract

To achieve thermoelectric energy conversion, a large transverse thermoelectric effect in topological materials is crucial. However, the general relationship between topological electronic structures and transverse thermoelectric effect remains unclear, restricting the rational design of novel transverse thermoelectric materials. Herein, we demonstrate a topological transition-induced giant transverse thermoelectric effect in polycrystalline Mn-doped Mg3+{\delta}Bi2 material, which has a competitively large transverse thermopower (617 uV/K), power factor (20393 uWm-1K-2), magnetoresistance (16600%), and electronic mobility (35280cm2V-1S-1). The high performance is triggered by the modulation of chemical pressure and disorder effects in the presence of Mn doping, which induces the transition from a topological insulator to a Dirac semimetal. The high-performance polycrystalline Mn-doped Mg3+{\delta} Bi2 described in this work robustly boosts transverse thermoelectric effect through topological phase transition, paving a new avenue for the material design of transverse thermoelectricity.