Large enhancement of thermopower at low magnetic field in compensated semimetals

Dirac and Weyl semimetals are promising candidates for high-efficiency thermoelectrics due to their gapless spectrum and high mobility. Recent experiments have shown that the thermopower of Dirac and Weyl materials can be enormously enhanced by a magnetic field, especially when the material exhibits nearly-complete compensation of electron and hole carriers. Here the authors study theoretically the thermopower of compensated conductors, and they show that a strong increase of thermopower with magnetic field arises generically in compensated systems even at relatively low field values. The full field dependence exhibits a number of different regimes, which are mapped out in detail.