Quantum theory of nonlinear magnetotransport in topological insulators

Increasing attention has been paid to nonlinear magnetotransport effects in topological insulators, which may be used as a powerful tool to probe the topological surface states and spin-orbit interaction. In this work, we theoretically investigate the nonlinear charge transport in a three-dimensional topological insulator by using a formal quantum approach. We find that both a longitudinal and a transverse nonlinear resistance may emanate from the interplay of the topological surface state with spin-momentum locking and random interfacial disorder. Interestingly, these nonlinear magnetoresistances can be significantly enhanced as the carrier density is reduced. And both of them exhibit unusual dependencies on the magnetic field, which make them differentiable from those that rely on hexagonal warping or current-induced spin polarization.