We employ Onsager’s irreversible thermodynamics (IrTh) to study the Inverse Edelstein effect (IEE) for a non-magnetic material (NM) adjacent to a topological insulator (TI) with a strong spin-orbit interaction. The TI surface state region is treated as quasi two-dimensional (2d). For the IEE, the source is a 3d spin flux incident from the NM that converts, at the NM/TI interface, to a quasi-2d charge current in the TI. For the Edelstein Effect (EE), the source is a quasi-2d charge flux incident from the TI that converts, at the interface, to a three-dimensional (3d) spin flux in the NM. For strong spin-orbit coupling, as considered here, when the 3d spin flux crosses to the 2d TI, the quasi-2d charge current is produced along with a quasi-2d spin accumulation. (For weak spin-orbit coupling, production of charge current and of spin accumulation are distinct processes.) We compute the associated rates of heating.
Spin-orbit torque in a three-dimensional topological insulator–ferromagnet heterostructure: Crossover between bulk and surface transport