Spin-charge coupled transport in topological-insulator-based heterostructures

Experimental advances have made possible the creation of heterostructures composed of two or more layers of two-dimensional systems that combine their individual properties to reach desired functionalities. In this talk, we present the spin-charge coupled diffusion equations for heterostructures with random interlayer tunneling and in which one of the layers has strong spin-orbit coupling. We consider two distinct regimes: the weak coupling regime, for which the disorder-induced scattering time is shorter than the tunneling-induced scattering time, and the strong coupling regime, for which random tunneling events are dominant. We then apply our formalism to the case in which a two-dimensional electron gas is placed in proximity to the surface of a three-dimensional topological insulator and discuss the relevance of our results for experiments.