Fig. 5.

Edelstein effect. Top: a Energy dispersion surfaces of the 2D states at a Rashba interface and b Dirac dispersion cone of the surface or interface states of a topological insulator. Bottom: a Fermi contours of Rashba states with two contours with helical spin configurations of opposite chirality and b TI surface or interface states. c, d Edelstein effect: A flow of electrons along x ($j_{\mathrm{c}}^{2D\left(x\right)}<0$ in the figure) in c Rashba or d TI. 2DEGs are associated with shifts $\mathrm{\Delta }k$ of the Fermi contours generating an extra population of spin along the direction. (For Rashba, there is a partial compensation of the contributions of the two contours.) e Schematic picture of intrinsic spin–orbit generated spin currents. An electric field in the x-direction displaces the Fermi distribution by $\delta k$. Carriers experience a torque that tilts them according to their spins. The tilting is opposite for opposite momenta and it generates a spin current in the y-direction.

Figures reprinted with permission from Ref. [113]