Spin and charge transport in the presence of spin-orbit interaction

We present the study of spin and charge transport in nanostructures in the presence of spin-orbit (SO) interaction. Single band tight binding Hamiltonians for Elliot-Yafet and Rashba SO interaction are derived. Using these tight binding Hamiltonians and spin resolved Landauer-Büttiker formula, spin and charge transport is studied. Specifically numerical results are presented for a new method to perform magnetic scanning tunneling microscopy with non-magnetic tip but in the presence of Elliot-Yafet SO interaction. The spin relaxation phenomena in two-dimensional electron gas in the presence of Rashba SO interaction are studied and contrary to naive expectation, it is shown that disorder helps to reduce spin relaxation.     

Contribution of spin-orbit interaction to the magnetic susceptibility of interacting electrons in metals

The effect of spin-orbit interaction on the magnetic susceptibility of metals has been investigated using a pseudopotential formalism. The orbital spin and spin-orbit contributions to the magnetic susceptibility of Zn and Cd have been calculated. An important feature is that the spin-orbit contribution is diamagnetic and is of the same order of magnitude as orbital contribution in the case of Zn and Cd.     

On the charge density modulation in the bunch by the interaction with electromagnetic wave

The efficiency of the charge density modulation of an electron bunch in the field of a linearly polarized monochromatic electromagnetic wave propagating oppositely to the bunch motion is considered. It is shown that as a result of the bunch-wave interaction the coherently radiating bunches can be obtained.     

A comparison between different models for the isotopic differences in lead

Using the density-dependent Hartree-Foxk approach as a reference, the isotopic shifts in lead are computed for several models: particle-vibration-coupling-plus-doorway-dominance, improved Thomas-Fermi, and droplet model. It is found that they agree in their overall predictions provided the same effective interaction is used in all cases. The accuracy of their results for the changes in proton radii at the shell closure is discussed in detail.     

Contribution to problem of interaction between h-f electromagnetic field and plasma

Magnetoactive plasma is regarded as an anisotropic compressible dielectric. A thermodynamical method is used to solve the interaction of plasma with an h-f field which fully penetrates into it. Assuming isothermicity, the equilibrium state is reached in the minima of free energy. The case of cylindrical configuration is solved in detail; the equilibrium plasma frequencies are determined. The influence of electron collision frequency is analyzed.In conclusion, the author thanks all members of the institute seminar for constructive criticism.     

The effect of spin-orbit splitting on the valence band density of states of lead

Tight-binding calculations are reported for the valence bands of lead, with and without spin-orbit splitting in the 6p bands. The addition of spin-orbit interaction is necessary to reproduce the two-peaked structure in the 6p density of states observed in X-ray photoemission, in contrast to the assertion by Breeze that crystal-field effects alone are enough. The observed splitting is, however, only fortuitously nearly equal to the atomic spin-orbit splitting. The tight-binding band structure, with spin-orbit splitting, gives better overall agreement with optical, Fermi surface, and photoemission data than did any of the three earlier band structures.     

Anisotropic interface contribution to the spin-orbit interaction in quantum wells

Experimental data on the anisotropy of electron spin resonance in a GaAs/AlGaAs quantum well have been interpreted. In has been shown that the spin-orbit interaction in quantum wells includes, in addition to the isotropic Bychkov-Rashba and anisotropic volume Dresselhaus contributions, the anisotropic contribution determined by the structure of interfaces.     

A discussion of the role of dispersion effects on isotopic charge density variations

The role of dispersion correction has been qualitatively studied in isotopic comparison experiments. The correction to elastic electron scattering for electrons of order 100 MeV from three isotopes of Titanium has been estimated using a code due to Rawitscher. The dispersion correction is found to produce variations in the ratio of the cross sections of nearby isotopes of a magnitude sufficient to cast doubt on the magnitude of the variations in charge density parameters.     

On the isotopic dependence of the mean spin-orbit field in nuclei

An analysis has been made of experimental data on level spectra, single-nucleon transfer reactions near closed shells, and data on the polarization effects in charge-exchange (p, n) reactions between isoanalog states of nuclei with even A. The analysis has allowed us to conclude that there is a significant difference between the spin-orbit splittings of neutrons and protons in identical orbitals. This conclusion is confirmed in a framework of different theoretical approaches.     

Dynamical suppression of the spin-orbit interaction in hadrons

A spin-dependent interaction in hadrons is considered in the approach of the QCD string. The string moment of inertia, which ensures the correct (inverse) Regge slope 2πσ, is found to suppress the spin-orbit interaction. For light quarks and moderate angular momenta, the suppression constitutes around 25%, whereas for large angular momenta the spin-orbit interaction is suppressed by the factor L ^−2/5. For heavy quarks, the effect manifests itself as a string correction for the spin-dependent potential. The text was submitted by the authors in English.     

Possibility of the charge density modulation of an electron bunch in the electromagnetic wave field

We consider the problem of modulation of the electron density in a linear bunch after its interaction with a linearly polarized, monochromatic electromagnetic wave, as well as an opportunity to observe this effect. It is shown that one can achieve significant values of the modulation depth at high intensities of the electromagnetic wave.     

Surface delta interaction and electromagnetic transitions in tin and lead isotopes

Electric Quadrupole and Octupole transition rates are calculated in even Pb and Sn isotopes using wavefunctions obtained with a Surface Delta Interaction. Agreement with experimental results is better than in previous calculations which used a Pairing plus Quadrupole (or Octupole) or a Gaussian Interaction.     

Elastic charge density representation of the interaction via the nematic director field

The interaction between particle-like sources of the nematic director distortions (e.g., colloids, point defects, macromolecules in nematic emulsions) allows for a useful analogy with the electrostatic multipole interaction between charged bodies. In this paper we develop this analogy to the level corresponding to the charge density and consider the general status of the pairwise approach to the nematic emulsions with finite-size colloids. It is shown that the elastic analog of the surface electric charge density is represented by the two transverse director components on the surface imposing the director distortions. The elastic multipoles of a particle are expressed as integrals over the charge density distribution on this surface. Because of the difference between the scalar electrostatics and vector nematostatics, the number of elastic multipoles of each order is doubled compared to that in the electrostatics: there are two elastic charges, two vectors of dipole moments, two quadrupolar tensors, and so on. The two-component elastic charge is expressed via the vector of external mechanical torque applied on the particle. As a result, the elastic Coulomb-like coupling between two particles is found to be proportional to the scalar product of the two external torques and does not directly depend on the particles' form and anchoring. The real-space Green function method is used to develop the pairwise approach to nematic emulsions and determine its form and restrictions. The pairwise potentials are obtained in the familiar form, but, in contrast to the electrostatics, they describe the interaction between pairs (dyads) of the elastic multipole moments. The multipole moments are shown to be uniquely determined by the single-particle director field, unperturbed by other particles. The pairwise approximation is applicable only in the leading order in the small ratio particle size-to-interparticle distance as the next order contains irreducible three-body terms.     

Light quark mass differences and charge symmetry breaking in hyperon-nucleon interaction

Quantum chromodynamics based isovector isoscolar particle mixing arising out of isospin violating quark mass differences has been used to construct a new charge-symmetry breaking Λ-N interaction element. It appears that vector meson exchanges between N and a physical Λ rather than pseudoscalar exchanges provide the largest contribution to explain the binding energy difference between the mirror hyper-nuclei _ΛHe⁴ and _ΛH⁴. Prediction of the model to Λn and Λp scattering lengths have been compared with those obtained from the combined analysis of ΛN scattering and s-shell hyperfragment data. We find satisfactory agreement of our results.     

Rashba spin-orbit interaction in graphene armchair nanoribbons

We study graphene nanoribbons (GNRs) with armchair edges in the presence of Rashba spin- orbit interactions (RSOI). We impose the boundary conditions on the tight binding Hamiltonians for bulk graphene with RSOI by means of a sine transform and study the influence of RSOI on the spectra and the spin polarization in detail. We derive the low energy approximation of the RSOI Hamiltonian for the zeroth and first order in momentum and test their ranges of validity. The choice of a basis appropriate for armchair boundaries is important in the case of mode-coupling effects and leads to results that are easy to work with.     

Baryon-baryon spin-orbit interaction in a quark model

The baryon-baryon spin-orbit interactions are studied within the framework of a nonrelativistic quark-cluster model. The origin of the spin-orbit interactions is taken to be the Galilei-invariant part of the spin-orbit term in the one-gluon-exchange potential between quarks. It gives, for example, the NN spin-orbit interaction which is qualitatively similar to the empirical ones. The baryon-nucleus spin-orbit interactions are also considered along this line. The N- and Σ-nucleus spin-orbit interactions are of comparable strength, while the Λ-nucleus spin-orbit interaction is weak. The main origin of the difference between the Λ -nucleus and Σ-nucleus spin-orbit interactions is the presence of the comparatively strong antisymmetric LS (ALS) terms for both NΛ and NΣ interactions but with opposite signs. Other sources of the spin-orbit interactions are briefly discussed in connection with the problem of the spin-orbit effect in the excited baryon spectra.     

Spin waves in cold gases with the spin-orbit interaction

A new type of spin waves that appear in cold paramagnetic gases owing to the spin-orbit interaction has been predicted. The Boltzmann gases of heavy atoms with a nonzero orbital angular momentum are considered. The dispersion relation of the spin waves is determined by the scattering amplitude due to the spin-orbit interaction.     

Enhancement of electron density in the interaction of high-power electromagnetic waves with inhomogeneous magnetized plasma

Propagation characteristics of a high-power electromagnetic wave through an inhomogeneous magnetized plasma is investigated. Considering the momentum transfer equations for electrons and ions and taking into account the ponderomotive force, the distribution of electron density and dielectric permittivity are obtained. Using non-linear dielectric permittivity and Maxwell's equations in the absence of external current and charge densities, non-linear wave equations are achieved. The results indicate that the external static magnetic field can modify the profiles of both the electric and magnetic fields. It is also shown that the external static magnetic field enhances the amplitude of the electron density and the non-linear dielectric permittivity.     

Ultrafast spin dynamics including spin-orbit interaction in semiconductors

This Letter presents a theoretical investigation of ultrafast spin-dependent carrier dynamics in semiconductors due to strong spin-orbit coupling using holes in bulk GaAs as a model system. By computing the microscopic carrier dynamics in the anisotropic hole-band structure including spin-orbit coupling, we obtain spin-relaxation times in quantitative agreement with measured hole-spin relaxation times [Phys. Rev. Lett. 89, 146601 (2002)10.1103/PhysRevLett.89.146601]. We show that different optical techniques for the measurement of hole-spin dynamics yield different results, in contrast to the case of electron-spin dynamics.