Abstract
Dirac semimetals (DSM) and Weyl semimetal (WSM) fall under the generic class of three-dimensional (3D) solids, which follow the relativistic energy-momentum relation at low energies. Such a linear dispersion when regularized on a lattice can lead to remarkable properties such as the anomalous Hall effect, the presence of Fermi surface arcs, positive longitudinal magnetoconductance, and dynamic chiral magnetic effect. The last two properties arise due to the manifestation of chiral anomaly in these semimetals, which refers to the nonconservation of chiral charge in the presence of electromagnetic gauge fields. Here we propose the planar Nernst effect, or transverse thermopower, as another consequence of chiral anomaly, which should occur in both Dirac and Weyl semimetals. We analytically calculate the planar Nernst coefficient for DSMs (type I and type II) and also WSMs (type I and type II) using a quasiclassical Boltzmann formalism. The planar Nernst effect manifests in a configuration when the applied temperature gradient, magnetic field, and the measured voltage are all coplanar and is of distinct origin when compared to the anomalous and conventional Nernst effects. Our findings, specifically a 3D map of the planar Nernst coefficient in type-I Dirac semimetals (, , etc.) and type-II DSM (, VAI3, etc.), can be verified experimentally by an in situ 3D double-axis rotation extracting the full solid angular dependence of the Nernst coefficient.
- Received 22 April 2019
- Revised 28 October 2019
DOI:https://doi.org/10.1103/PhysRevB.100.195113
©2019 American Physical Society