Long-range effect of a Zeeman field on the electric current through the helical metal-superconductor interface in Andreev interferometer

It is shown that the spin-orbit and Zeeman interactions result in phase shifts of Andreev-reflected holes in disordered topological insulator, or normal Rashba spin-orbit-coupled wires, which are in a contact with an s-wave superconductor. Due to interference of the holes reflected through different paths in Andreev interferometer the electric current through the contact varies depending on the strength and direction of the Zeeman field. It also depends on mutual orientations of Zeeman fields in different shoulders of the interferometer. Such a nonlocal effect is a result of the long-range coherency caused by the superconducting proximity effect. This current has been calculated within the semiclassical theory for Green functions of a dirty system.Comment: 7 pages, final versio

Spin transmission through quantum dots with strong spin-orbit interaction

Quantum oscillations of the spin conductance through regular and chaotic 2D quantum dots under the varying Rashba spin orbit interaction and at zero magnetic field have been numerically calculated by summing up the spin evolution matrices for classical transmitting trajectories. Fourier analysis of these oscillations showed power spectra strongly dependent on the dot geometry. For narrow rings the spectra are dominated by a single peak in accordance with previous analytic results. In other geometries the spectra are represented by multiple peaks for regular QD and quasicontinuum for chaotic QD.Comment: 10 pages, 5 figure

Edge bands and vertical transport in topological insulator/magnetic insulator heterostructures

The low-energy band-structure of electrons propagating on a lateral surface of a heterostructure consisting of three dimensional topological insulator (TI) and magnetic insulator layers has been calculated. The energy spectrum is highly tunable depending on the relation between the interlayer tunneling amplitude, Zeeman energy and surface potential. A ratio between the first two parameters controls a topological transition between chiral and helical surface state band-structures. In the former case localized states, whose wave-functions are confined near single TI layers, emerge in a narrow parameter range where they coexist with itinerant states. In regular superlattices these localized states form a flat band in the vertical direction. Such a localization has a topological origin. It is associated with a specific spatial spin texture of these states. The localized states vanish upon the topological phase transition from the anomalous quantum Hall regime to a trivial phase characterized by an anisotropic Dirac cone on the lateral surface of the heterostructure.Comment: 9 pages, 7 figure

Generation of spin current and polarization under dynamic gate control of spin-orbit interaction in low-dimensional semiconductor systems

Based on the Keldysh formalism, the Boltzmann kinetic equation and the drift diffusion equation have been derived for studying spin polarization flow and spin accumulation under effect of the time dependent Rashba spin-orbit interaction in a semiconductor quantum well. The time dependent Rashba interaction is provided by time dependent electric gates of appropriate shapes. Several examples of spin manipulation by gates have been considered. Mechanisms and conditions for obtaining the stationary spin density and the induced rectified DC spin current are studied.Comment: 10 pages, 3 figures, RevTeX

Quantum oscillations of spin current through a III-V semiconductor loop

We have investigated the transport of spin polarization through a classically chaotic semiconductor loop with a strong Rashba spin-orbit interaction. We found that if the escape time of a particle is long enough, the configuration averaged spin conductance oscillates strongly with the geometric spin phase. We predict a sizable rotation of spin polarization along its flowing path across the loop from the injector to the collector. We have also discovered a quantized universal spin relaxation in a 2D reservoir connected to such a semiconductor loop.Comment: 4 pages, 1 figur

Nonuniversality of the intrinsic inverse spin-Hall effect in diffusive systems

We studied the electric current induced in a two-dimensional electron gas by the spin current, in the presence of Rashba and cubic Dresselhaus spin-orbit interactions. We found out that the factor relating these currents is not universal, but rather depends on the origin of the spin current. Drastic distinction has been found between two cases: the spin current created by diffusion of an inhomogeneous spin density, and the pure homogeneous spin current. We found out that in the former case the ISHE electric current is finite, while it turns to zero in the latter case, if the spin-orbit coupling is represented by Rashba interaction.Comment: 1 figur