Cosimo Gorini

Quasiclassical approach to the spin-Hall effect in the two-dimensional electron gas

We study the spin-charge coupled transport in a two-dimensional electron system using the method of quasiclassical (

Spin-orbit interaction in a two-dimensional electron gas: A SU(2) formulation†

\ensuremath{\xi}

Spin-charge locking and tunneling into a helical metal

-integrated) Greens functions. In particular we derive the Eilenberger equation in the presence of a generic spin-orbit field. The method allows us to study spin and charge transport from ballistic to diffusive regimes and continuity equations for spin and charge are automatically incorporated. In the clean limit we establish the connection between the spin Hall conductivity and the Berry phase in momentum space. For finite systems we solve the Eilenberger equation numerically for the special case of the Rashba spin-orbit coupling and a two-terminal geometry. In particular, we calculate explicitly the spin Hall induced spin polarization in the corners, predicted by Mishchenko et al. [Phys. Rev. Lett. 93, 226602 (2004)]. Furthermore we find universal spin currents in the short-time dynamics after switching on the voltage across the sample, and calculate the corresponding spin Hall polarization at the edges. Where available, we find perfect agreement with analytical results.

Non-Abelian gauge fields in the gradient expansion: Generalized Boltzmann and Eilenberger equations

Spin-orbit interaction is usefully classified as extrinsic or intrinsic, depending on its origin: the potential due to random impurities (extrinsic), or the crystalline potential associated with the band or device structure (intrinsic). In this paper we will show how, by using a SU(2) formulation, the two sources may be described in an elegant and unified way. As a result we obtain a simple description of the interplay of the two types of spin-orbit interaction, and a physically transparent explanation of the vanishing of the d.c. spin Hall conductivity in a Rashba two-dimensional electron gas when spin relaxation is neglected, as well as its reinstatement when spin relaxation is allowed. Furthermore, we obtain an explicit formula for the transverse spin polarization created by an electric current, which generalizes the standard formula obtained by Edelstein, and Aronov and Lyanda-Geller by including extrinsic spin-orbit interaction and spin relaxation.

Spin polarizations and spin Hall currents in a two-dimensional electron gas with magnetic impurities

We derive a kinetic equation for the electrons moving on the surface of a three-dimensional topological insulator. Due to the helical nature of the excitations backward scattering is suppressed in the collision integral, and the spin dynamics is entirely constrained by that of the charge. We further analyze the tunneling between the helical metal and a conventional metal or ferromagnet. We find that the tunnel resistance strongly depends on the angle between the magnetization in the ferromagnet and the current in the helical metal. A nonmagnetic layer on top of the helical metal amplifies the current-induced spin polarization.

Spin relaxation in narrow wires of a two-dimensional electron gas

We present a microscopic derivation of the generalized Boltzmann and Eilenberger equations in the presence of non-Abelian gauges for the case of a nonrelativistic disordered Fermi gas. A unified and symmetric treatment of the charge

Room temperature spin thermoelectrics in metallic films

[U(1)]

Spin thermoelectrics in a disordered Fermi gas

and spin

Inverse Spin Hall Effect and Anomalous Hall Effect in a Two-Dimensional Electron Gas

[SU(2)]

Theory of current-induced spin polarization in an electron gas

degrees of freedom is achieved. Within this framework, just as the