Spin-Hall conductivity of a disordered 2D electron gas with Dresselhaus spin-orbit interaction

The spin-Hall conductivity of a disordered 2D electron gas has been calculated for an arbitrary spin-orbit interaction. We have found that in the diffusive regime of electron transport, in accordance with previous calculations, the dc spin-Hall conductivity of a homogeneous system turns to zero due to impurity scattering when the spin-orbit coupling is represented only by the Rashba interaction. However, when the Dresselhaus interaction is taken into account, the spin-Hall current is not zero. We also considered the spin-Hall currents induced by an inhomogeneous electric field. It is shown that a time dependent electric charge induces a vortex of spin-Hall currents.Comment: 5 pages, figure adde

Probing a non-biaxial behavior of infinitely thin hard platelets

We give a criterion to test a non-biaxial behavior of infinitely thin hard platelets of $D_{2h}$ symmetry based upon the components of three order parameter tensors. We investigated the nematic behavior of monodisperse infinitely thin rectangular hard platelet systems by using the criterion. Starting with a square platelet system, and we compared it with rectangular platelet systems of various aspect ratios. For each system, we performed equilibration runs by using isobaric Monte Carlo simulations. Each system did not show a biaxial nematic behavior but a uniaxial nematic one, despite of the shape anisotropy of those platelets. The relationship between effective diameters by simulations and theoretical effective diameters of the above systems was also determined.Comment: Submitted to JPS

Suppression of the D'yakonov-Perel' spin relaxation mechanism for all spin components in [111] zincblende quantum wells

We apply the D'yakonov-Perel' (DP) formalism to [111]-grown zincblende quantum wells (QWs) to compute the spin lifetimes of electrons in the two-dimensional electron gas. We account for both bulk and structural inversion asymmetry (Rashba) effects. We see that, under certain conditions, the spin splitting vanishes to first order in k, which effectively suppresses the DP spin relaxation mechanism for all spin components. We predict extended spin lifetimes as a result, giving rise to the possibility of enhanced spin storage. We also study [110]-grown QWs, where the effect of structural inversion asymmetry is to augment the spin relaxation rate of the component perpendicular to the well. We derive analytical expressions for the spin lifetime tensor and its proper axes, and see that they are dependent on the relative magnitude of the BIA- and SIA-induced splittings.Comment: v1: 5 pages, 2 figures, submitted to PRL v2: added 1 figure and supporting content, PRB forma

Fluids of platelike particles near a hard wall

Fluids consisting of hard platelike particles near a hard wall are investigated using density functional theory. The density and orientational profiles as well as the surface tension and the excess coverage are determined and compared with those of a fluid of rodlike particles. Even for low densities slight orientational packing effects are found for the platelet fluid due to larger intermolecular interactions between platelets as compared with those between rods. A net depletion of platelets near the wall is exhibited by the excess coverage, whereas a change of sign of the excess coverage of hard-rod fluids is found upon increasing the bulk density.Comment: 6 pages, 9 figure

Quantum oscillations in the transverse voltage of a channel in the non-linear transport regime

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Spin Orientation and Spin Precession in Inversion-Asymmetric Quasi Two-Dimensional Electron Systems

Inversion asymmetry induced spin splitting of the electron states in quasi two-dimensional (2D) systems can be attributed to an effective magnetic field B which varies in magnitude and orientation as a function of the in-plane wave vector k||. Using a realistic 8x8 Kane model that fully takes into account spin splitting because of both bulk inversion asymmetry and structure inversion asymmetry we investigate the spin orientation and the effective field B for different configurations of a quasi 2D electron system. It is shown that these quantities depend sensitively on the crystallographic direction in which the quasi 2D system was grown as well as on the magnitude and orientation of the in-plane wave vector k||. These results are used to discuss how spin-polarized electrons can precess in the field B(k||). As a specific example we consider GaInAs-InP quantum wells.Comment: 10 pages, 6 figure

Spin relaxation dynamics of quasiclassical electrons in ballistic quantum dots with strong spin-orbit coupling

We performed path integral simulations of spin evolution controlled by the Rashba spin-orbit interaction in the semiclassical regime for chaotic and regular quantum dots. The spin polarization dynamics have been found to be strikingly different from the D'yakonov-Perel' (DP) spin relaxation in bulk systems. Also an important distinction have been found between long time spin evolutions in classically chaotic and regular systems. In the former case the spin polarization relaxes to zero within relaxation time much larger than the DP relaxation, while in the latter case it evolves to a time independent residual value. The quantum mechanical analysis of the spin evolution based on the exact solution of the Schroedinger equation with Rashba SOI has confirmed the results of the classical simulations for the circular dot, which is expected to be valid in general regular systems. In contrast, the spin relaxation down to zero in chaotic dots contradicts to what have to be expected from quantum mechanics. This signals on importance at long time of the mesoscopic echo effect missed in the semiclassical simulations.Comment: 14 pages, 9 figure

Mesoscopic spin confinement during acoustically induced transport

Long coherence lifetimes of electron spins transported using moving potential dots are shown to result from the mesoscopic confinement of the spin vector. The confinement dimensions required for spin control are governed by the characteristic spin-orbit length of the electron spins, which must be larger than the dimensions of the dot potential. We show that the coherence lifetime of the electron spins is independent of the local carrier densities within each potential dot and that the precession frequency, which is determined by the Dresselhaus contribution to the spin-orbit coupling, can be modified by varying the sample dimensions resulting in predictable changes in the spin-orbit length and, consequently, in the spin coherence lifetime.Comment: 10 pages, 2 figure