Phonon-limited mobility of Dirac fermions in three-dimensional Dirac semimetal Cd3As2

Abstract

A theoretical model is presented for the phonon-limited mobility of the Dirac fermion gas in three-dimensional (3D) Dirac semimetal Cd3As2, with consideration of the scattering from both the acoustic and optical phonons. Screening effects are taken into account and it is found that they lead to significant enhancement of the mobility. Simple analytical equations and power laws are obtained for both the Bloch–Grüneisen and equipartition regimes. The dependence of the mobility on the temperature T and electron density ne is investigated. The optical-phonon-limited mobility μop is found to dominate over the acoustic-phonon-limited mobility μap in the higher-temperature region. There is a crossover of μap and μop, and the crossover temperature Tc shifts to a higher value with increasing ne. Numerical calculations of the mobility are conducted for recently reported experimental samples and good agreement is obtained with the experimental results. A comparison is also made with the results for a conventional 3D electron gas in a degenerate semiconductor.