Spin Hall Effect and Spin Orbit coupling in Ballistic Nanojunctions

We propose a new scheme of spin filtering based on nanometric crossjunctions in the presence of Spin Orbit interaction, employing ballistic nanojunctions patterned in a two-dimensional electron gas. We demonstrate that the flow of a longitudinal unpolarized current through a ballistic X junction patterned in a two-dimensional electron gas with Spin Orbit coupling (SOC) induces a spin accumulation which has opposite signs for the two lateral probes. This spin accumulation, corresponding to a transverse pure spin current flowing in the junction, is the main observable signature of the spin Hall effect in such nanostructures. We benchmark the effects of two different kinds of Spin Orbit interactions. The first one ($\alpha$-SOC) is due to the interface electric field that confines electrons to a two-dimensional layer, whereas the second one ($\beta$-SOC) corresponds to the interaction generated by a lateral confining potential.Comment: 6 pages, 3 figure

Observation of exchange Coulomb interactions in the quantum Hall state at nu=3

Coulomb exchange interactions of electrons in the nu=3 quantum Hall state are determined from two inter-Landau level spin-flip excitations measured by resonant inelastic light scattering. The two coupled collective excitations are linked to inter-Landau level spin-flip transitions arising from the N=0 and N=1 Landau levels. The strong repulsion between the two spin-flip modes in the long-wave limit is clearly manifested in spectra displaying Coulomb exchange contributions that are comparable to the exchange energy for the quantum Hall state at nu=1. Theoretical calculations within the Hartree-Fock approximation are in a good agreement with measured energies of spin-flip collective excitations.Comment: 5 pages, 3 figures, to appear in PRB Rapid Communication

Spin relaxation of two-dimensional electrons with a hierarchy of spin-orbit couplings

The density matrix formalism is applied to calculate the spin-relaxation time for two-dimensional systems with a hierarchy of spin-orbit couplings, such as Rashba-type, Dresselhaus-type and so on. It is found that the spin-relaxation time can be infinite if those coupling strengths $\alpha$, $\beta$, $\gamma_1$ and $\gamma_2$ satisfy either condition (i) $\alpha=\beta, \gamma_1=0$ or (ii) $\alpha=-\beta, \gamma_2=0$, which correspond to the vanishing Yang-Mills "magnetic" field. The effect caused by the application of an external magnetic field is also discussed. It is found that the longitudinal and in-plane spin components can possess infinite life time when the spin components, the Larmor precession frequency and the external magnetic field satisfy certain relations.Comment: Revtex, 7 pages, 3 figure

Quantum Electrodynamics and the Origins of the Exchange, Dipole-Dipole, and Dzyaloshinsky-Moriya Interactions in Itinerant Fermion Systems

It is shown how the exchange interaction, the dipole-dipole interaction, and the Dzyaloshinsky-Moriya interaction between electronic spin-density fluctuations emerge naturally from a field-theoretic framework that couples electrons to the fluctuating electromagnetic potential. Semi-quantitative estimates are given to determine when the dipole-dipole interaction, which is often neglected, needs to be considered, and various applications are discussed, with an emphasis on weak ferromagnets and on helimagnets.Comment: 12pp, 3 fig

Slowing down of spin relaxation in two dimensional systems by quantum interference effects

The effect of weak localization on spin relaxation in a two-dimensional system with a spin-split spectrum is considered. It is shown that the spin relaxation slows down due to the interference of electron waves moving along closed paths in opposite directions. As a result, the averaged electron spin decays at large times as $1/t$. It is found that the spin dynamics can be described by a Boltzmann-type equation, in which the weak localization effects are taken into account as nonlocal-in-time corrections to the collision integral. The corrections are expressed via a spin-dependent return probability. The physical nature of the phenomenon is discussed and it is shown that the "nonbackscattering" contribution to the weak localization plays an essential role. It is also demonstrated that the magnetic field, both transversal and longitudinal, suppresses the power tail in the spin polarization.Comment: 12 pages, 2 figure

Spin interference in silicon three-terminal one-dimensional rings

We present the first findings of the spin transistor effect in the Rashba gate-controlled ring embedded in the p-type self-assembled silicon quantum well that is prepared on the n-type Si (100) surface. The coherence and phase sensitivity of the spin-dependent transport of holes are studied by varying the value of the external magnetic field and the bias voltage that are applied perpendicularly to the plane of the double-slit ring. Firstly, the amplitude and phase sensitivity of the 0.7(2e^2/h) feature of the hole quantum conductance staircase revealed by the quantum point contact inserted in the one of the arms of the double-slit ring are found to result from the interplay of the spontaneous spin polarization and the Rashba spin-orbit interaction. Secondly, the quantum scatterers connected to two one-dimensional leads and the quantum point contact inserted are shown to define the amplitude and the phase of the Aharonov-Bohm and the Aharonov-Casher conductance oscillations.Comment: 8 pages, 5 figure

Triplet pairing due to spin-orbit-assisted electron-phonon coupling

We propose a microscopic mechanism for triplet pairing due to spin-orbit-assisted electron interaction with optical phonons in a crystal with a complex unit cell. Using two examples of electrons with symmetric Fermi surfaces in crystals with either a cubic or a layered square lattice, we show that spin-orbit-assisted electron-phonon coupling can, indeed, generate triplet pairing and that, in each case, it predetermines the tensor structure of a p-wave order parameter

Direct coupling between magnetism and superconducting current in Josephson Phi junction

We study the proximity effect between conventional superconductor and magnetic normal metal with a spin-orbit interaction of the Rashba type. Using the phenomenological Ginzburg-Landau theory and the quasiclassical Eilenberger approach it is demonstrated that the Josephson junction with such a metal as a weak link has a special non-sinusoidal current-phase relation. The ground state of this junction is caracterized by the finite phase difference Phi, which is proportional to the strength of the spin-orbit interaction and the exchange field in the normal metal. The proposed mechanism of the Phi junction formation gives a direct coupling between the superconducting current and the magnetic moment in the weak link. Therefore the Phi junctions open interesting perspectives for the superconducting spintronics

Innovative approaches in assessing social and economic damage from road accidents

The article is devoted to the review of approaches and analysis of methods for assessing the cost of social and economic damage from road accidents. The urgency of the problem is determined by the high rates of accidents and deaths. Social and economic consequences of non-underestimation of human life in the country can negatively affect the individual quality of life of Russians, and state level in the form of damage from losses of the economically active population and the state's compensation for damages to the families of victims. Therefore, the development of new theoretical approaches to assess social and economic damage from accidents, which meet modern conditions, has become of particular relevance in Russia. The article considers methodological peculiarities of accounting and assessment of the consequences of road accidents both within the framework of international experience and within the framework of the Russian Federation, which has allowed developing scientifically grounded approach to assessing damage from road accidents in our country, this in its turn contributes to reducing mortality rates through development and financial support of road safety programs. Based on the author's research, an innovative approach to assessing social and economic losses from road accidents in the Russian Federation has been formed, which focuses on damage resulting from death and injury of people, taking into account age and gender structure of the deceased, wounded people and regional characteristics, damage as a result of damage to vehicles and goods, damage as a result of damage to roads and road structures, as well as moral damage.peer-reviewe

Rashba coupling in quantum dots: exact solution

We present an analytic solution to the problem of the Rashba spin-orbit coupling in semiconductor quantum dots. We calculate the exact energy spectrum, wave-functions, and spin--flip relaxation times. We discuss various effects inaccessible via perturbation theory. In particular, we find that the effective gyromagnetic ratio is strongly suppressed by the spin-orbit coupling. The spin-flip relaxation rate has a maximum as a function of the spin-orbit coupling and is therefore suppressed in both the weak- and strong coupling limits.Comment: 5 pages, 4 figs, reference adde