Anomalous magneto-thermoelectric behavior in massive Dirac materials

TL;DR

This paper reports a novel magneto-thermoelectric behavior in massive Dirac material ZrTe5, showing negative MTP in perpendicular fields and positive MTP in parallel fields, attributed to impurity scattering effects.

Contribution

It reveals a new type of magneto-thermoelectric response in ZrTe5, highlighting the role of impurity scattering in Dirac materials' transport phenomena.

Findings

Negative MTP observed in perpendicular magnetic fields.

Positive MTP observed in parallel magnetic fields.

Theoretical analysis links behavior to screened Coulomb scattering.

Abstract

Extensive studies of electron transport in Dirac materials have shown positive magneto-resistance (MR) and positive magneto-thermopower (MTP) in a magnetic field perpendicular to the excitation current or thermal gradient. In contrast, measurements of electron transport often show a negative longitudinal MR and negative MTP for a magnetic field oriented along the excitation current or thermal gradient; this is attributed to the chiral anomaly in Dirac materials. Here, we report a very different magneto-thermoelectric transport behavior in the massive Dirac material ZrTe5. Although thin flakes show a commonly observed positive MR in a perpendicular magnetic field, distinct from other Dirac materials, we observe a sharp negative MTP. In a parallel magnetic field, we still observe a negative longitudinal MR, however, a remarkable positive MTP is observed for the fields parallel to the thermal gradients. Our theoretical calculations suggest that this anomalous magneto-thermoelectric behavior can be attributed to the screened Coulomb scattering. This work demonstrates the significance of impurity scattering in the electron transport of topological materials and provides deep insight into the novel magneto-transport phenomena in Dirac materials.