7 research outputs found
Shot Noise of Spin-Decohering Transport in Spin-Orbit Coupled Nanostructures
We generalize the scattering theory of quantum shot noise to include the full
spin-density matrix of electrons injected from a spin-filtering or
ferromagnetic electrode into a quantum-coherent nanostructure governed by
various spin-dependent interactions. This formalism yields the spin-resolved
shot noise power for different experimental measurement setups--with
ferromagnetic source and ferromagnetic or normal drain electrodes--whose
evaluation for the diffusive multichannel quantum wires with the Rashba (SO)
spin-orbit coupling shows how spin decoherence and dephasing lead to
substantial enhancement of charge current fluctuations (characterized by Fano
factors ). However, these processes and the corresponding shot noise
increase are suppressed in narrow wires, so that charge transport experiments
measuring the Fano factor in a
ferromagnet/SO-coupled-wire/paramagnet setup also quantify the degree of
phase-coherence of transported spin--we predict a one-to-one correspondence
between the magnitude of the spin polarization vector and .Comment: 8 pages, 3 figure; enhanced with 2 new figure
Spin and Charge Shot Noise in Mesoscopic Spin Hall Systems
Injection of unpolarized charge current through the longitudinal leads of a
four-terminal two-dimensional electron gas with the Rashba spin-orbit (SO)
coupling and/or SO scattering off extrinsic impurities is responsible not only
for the pure spin Hall current in the transverse leads, but also for random
time-dependent current fluctuations. We employ the scattering approach to
current-current correlations in multiterminal nanoscale conductors to analyze
the shot noise of transverse pure spin Hall and zero charge current, or
transverse spin current and non-zero charge Hall current, driven by unpolarized
or spin-polarized longitudinal current, respectively. Since any spin-flip acts
as an additional source of noise, we argue that these shot noises offer a
unique tool to differentiate between intrinsic and extrinsic SO mechanisms
underlying the spin Hall effect in paramagnetic devices.Comment: 5 pages, 2 figures (5 embedded EPS files
Spin relaxation: From 2D to 1D
In inversion asymmetric semiconductors, spin-orbit interactions give rise to
very effective relaxation mechanisms of the electron spin. Recent work, based
on the dimensionally constrained D'yakonov Perel' mechanism, describes
increasing electron-spin relaxation times for two-dimensional conducting layers
with decreasing channel width. The slow-down of the spin relaxation can be
understood as a precursor of the one-dimensional limit
What can we learn about the dynamics of transported spins by measuring shot noise in spin–orbit-coupled nanostructures?
Computational study of the CO adsorption and diffusion in zeolites: validating the Reed–Ehrlich model
Calculation of the Absolute Free Energy of Binding and Related Entropies with the HSMD-TI Method: The FKBP12-L8 Complex
Dynamic spin-polarized shot noise in a quantum dot coupled to ferromagnetic terminals under the perturbation of ac fields
We have investigated the shot noise in the mesoscopic system composed of a quantum dot (QD) coupled to ferromagnetic terminals under the perturbation of ac fields. The shot noise has been derived using the nonequilibrium Green's function (NGF) technique to describe the spin polarization effect along with photon absorption and emission processes in the Coulomb blockade regime. We have examined the influence of spin polarization on the shot noise under the perturbation of ac fields in the nonadiabatic regime. The Coulomb blockade effect results in the modification of shot noise compared with the noninteracting case. The spin orientation contributes a spin valve effect for controlling electron tunnelling through this QD, and different resonant forms appear around the Coulomb blockade channel. The photon-assisted spin-splitting and spin-polarization effect contributes a photon-assisted spin valve to adjust the electron tunnelling current and shot noise. The spin-polarization effect varies the value of the Fano factor. However, it does not change the noise type from sub-Poissonian to super-Poissonian. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2010