Nernst and magnetothermal conductivity in a lattice model of Weyl fermions

Weyl semimetals (WSMs) are topologically protected three-dimensional materials whose low-energy excitations are linearly dispersing massless Dirac fermions, possessing a nontrivial Berry curvature. Using semiclassical Boltzmann dynamics in the relaxation time approximation for a lattice model of time-reversal (TR) symmetry broken WSMs, we compute both magnetic field dependent and anomalous contributions to the Nernst coefficient. In addition to the magnetic field dependent Nernst response, which is present in both Dirac and Weyl semimetals, we show that, contrary to previous reports, the TR-broken WSM also has an anomalous Nernst response due to a nonvanishing Berry curvature. We also compute the thermal conductivities of a WSM in the Nernst (TB) and the longitudinal (TB) setup and confirm from our lattice model that in the parallel setup, the Wiedemann-Franz law is violated between the longitudinal thermal and electrical conductivities due to the chiral anomaly.