1,216 research outputs found

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

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

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 $\phi$. 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 $\phi$ 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

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

We derive a closed-form expression for the weak localization (WL) corrections
to the magnetoconductivity of a 2D electron system with arbitrary Rashba
$\alpha$ and Dresselhaus $\beta$ (linear) and $\beta_3$ (cubic) spin-orbit
interaction couplings, in a perpendicular magnetic field geometry. In a system
of reference with an in-plane $\hat{z}$ axis chosen as the high spin-symmetry
direction at $\alpha = \beta$, 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
$\hat{z}$, dependent only on $\alpha - \beta$. 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 $\alpha/\beta$. 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

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

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