Abstract
Recent experiments performed the nonreciprocal magneotransport in ZrTe₅ and obtained a giant magnetochiral anisotropy (MCA) coefficient γ'. The existing theoretical analysis was based on the semiclassical Boltzmann equation. In this paper, we develop a full quantum theory to calculate γ' and further explore the underlying physics. We reveal that the xz-mirror symmetry breaking term also breaks the parity symmetry of the system and leads to mixed selection rules and nonvanishing second-order conductivity σ_xxx. The calculations show that γ' decreases with the magnetic field, survives only to weak impurity scatterings, and exhibits a nonmonotonous dependence on the strength of the xz-mirror symmetry breaking. Our paper can provide a deeper insight into the intrinsic nonreciprocal magnetotransport phenomena in the topological semimetal material.