1,216 research outputs found

    Electron-Dephasing Time in a Two-Dimensional Spin-Polarized System with Rashba Spin-Orbit Interaction

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    We calculate the dephasing time Bof an electron in a two-dimensional system with a Rashba spin-orbit interaction, spin-polarized by an arbitrarily large magnetic field parallel to the layer. B is estimated from the logarithmic corrections to the conductivity within a perturbative approach that assumes weak, isotropic disorder scattering. For any value of the magnetic field, the dephasing rate changes with respect to its unpolarized-state value by a universal function whose parameter is 2EZ=ESOI (EZ is the Zeeman energy, while ESOI is the spin-orbit interaction), confirming the experimental report published in Phys. Rev. Lett. 94, 186805 (2005). In the high-field limit, when 2EZ ESOI, the dephasing rate saturates and reaches asymptotically to a value equal to half the spin-relaxation rate

    Non-adiabatic generation of a pure spin current in a 1D quantum ring with spin-orbit interaction

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    We demonstrate the theoretical possibility of obtaining a pure spin current in a 1D ring with spin-orbit interaction by irradiation with a non-adiabatic, two-component terahertz laser pulse, whose spatial asymmetry is reflected by an internal dephasing angle ϕ\phi. The stationary solutions of the equation of motion for the density operator are obtained for a spin-orbit coupling linear in the electron momentum (Rashba) and used to calculate the time-dependent charge and spin currents. We find that there are critical values of ϕ\phi at which the charge current disappears, while the spin current reaches a maximum or a minimum value.Comment: 8 pages, 5 figure

    Topological thermoelectric effects in spin-orbit coupled electron and hole doped semiconductors

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    We compute the intrinsic contributions to the Berry-phase mediated anomalous Hall and Nernst effects in electron- and hole-doped semiconductors in the presence of an in-plane magnetic field as well as Rashba and Dresselhaus spin orbit couplings. For both systems we find that the regime of chemical potential which supports the topological superconducting state in the presence of superconducting proximity effect can be characterized by plateaus in the topological Hall and Nernst coefficients flanked by well-defined peaks marking the emergence of the topological regime. The plateaus arise from a clear momentum space separation between the region where the Berry curvature is peaked (at the `near-band-degeneracy' points) and the region where the single (or odd number of) Fermi surface lies in the Brillouin zone. The plateau for the Nernst coefficient is at vanishing magnitudes surrounded by two peaks of opposite signs as a function of the chemical potential. These results could be useful for experimentally deducing the chemical potential regime suitable for realizing topological states in the presence of proximity effect.Comment: 8 pages, 8 figure

    Closed-form weak localization magnetoconductivity in quantum wells with arbitrary Rashba and Dresselhaus spin-orbit interactions

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    We derive a closed-form expression for the weak localization (WL) corrections to the magnetoconductivity of a 2D electron system with arbitrary Rashba α\alpha and Dresselhaus β\beta (linear) and β3\beta_3 (cubic) spin-orbit interaction couplings, in a perpendicular magnetic field geometry. In a system of reference with an in-plane z^\hat{z} axis chosen as the high spin-symmetry direction at α=β\alpha = \beta, we formulate a new algorithm to calculate the three independent contributions that lead to WL. The antilocalization is counterbalanced by the term associated with the spin-relaxation along z^\hat{z}, dependent only on αβ\alpha - \beta. The other term is generated by two identical scattering modes characterized by spin-relaxation rates which are explicit functions of the orientation of the scattered momentum. Excellent agreement is found with data from GaAs quantum wells, where in particular our theory correctly captures the shift of the minima of the WL curves as a function of α/β\alpha/\beta. This suggests that the anisotropy of the effective spin relaxation rates is fundamental to understanding the effect of the SO coupling in transport.Comment: 5 pages, 2 figure

    Thermodynamic Limits of the Local Field Corrections in a Spin-Polarized Electron System

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    In a spin-polarized electron gas, the effect of the exchange ͑x͒ and correlation ͑c͒ interactions can be incorporated into the dynamic response functions through spin-dependent local-field corrections G␴ x,c(␻,qជ). We obtain the zero-frequency and long-wavelength limits of G␴ x,c(␻,qជ) by analyzing the connection between the macroscopic response function and the thermodynamic parameters of the system