Spin rotation for ballistic electron transmission induced by spin-orbit interaction

We study spin dependent electron transmission through one- and two-dimensional curved waveguides and quantum dots with account of spin-orbit interaction. We prove that for a transmission through arbitrary structure there is no spin polarization provided that electron transmits in isolated energy subband and only two leads are attached to the structure. In particular there is no spin polarization in the one-dimensional wire for which spin dependent solution is found analytically. The solution demonstrates spin evolution as dependent on a length of wire. Numerical solution for transmission of electrons through the two-dimensional curved waveguides coincides with the solution for the one-dimensional wire if the energy of electron is within the first energy subband. In the vicinity of edges of the energy subbands there are sharp anomalies of spin flipping.Comment: 9 oages, 7 figure

Electrostatic screening and Friedel oscillations in semiconducting nanotubes

In 3D and 2D electronic systems the singular contribution to the static permittivity ε (Kohn singularity) is a small correction to the regular part of ε but it results in the leading term in asymptotic behavior of the screened potential (Friedel oscillations). In the present letter we show that for nanotubes quite different results are valid: ε becomes infinitely large at the singular point and the Friedel oscillations do not play the dominant role in the screening at the large distances. Moreover, the zero and highest cylindrical harmonics of the effective potential are screened by quite different mechanisms

Conductance of tubular nanowires with disorder

We calculate the conductance of tubular-shaped nanowires having many potential scatterers at random positions. Our approach is based on the scattering matrix formalism and our results analyzed within the scaling theory of disordered conductors. When increasing the energy the conductance for a big enough number of impurities in the tube manifests a systematic evolution from the localized to the metallic regimes. Nevertheless, a conspicuous drop in conductance is predicted whenever a new transverse channel is open. Comparison with the semiclassical calculation leading to purely ohmic behavior is made.Comment: 8 pages, 5 figure

Theory of the charged Bose gas: Bose-Einstein condensation in an ultrahigh magnetic field

This article was published in the journal, Physical Review B [© American Physical Society]. It is also available at: http://link.aps.org/abstract/PRB/v54/p15363.The Bogoliubov-de Gennes equations and the Ginzburg-Landau-Abrikosov-Gor'kov-type theory are formulated for the charged Bose gas (CBG). The theory of the Bose-Einstein condensation of the CBG in a magnetic field is extended to ultralow temperatures and ultrahigh magnetic fields. A low-temperature dependence of the upper critical field Hc2(T) is obtained both for the particle-impurity and particle-particle scattering. The normal-state collective plasmon mode in ultrahigh magnetic fields is studied

Effect of the Surface on the Electron Quantum Size Levels and Electron g-Factor in Spherical Semiconductor Nanocrystals

The structure of the electron quantum size levels in spherical nanocrystals is studied in the framework of an eight--band effective mass model at zero and weak magnetic fields. The effect of the nanocrystal surface is modeled through the boundary condition imposed on the envelope wave function at the surface. We show that the spin--orbit splitting of the valence band leads to the surface--induced spin--orbit splitting of the excited conduction band states and to the additional surface--induced magnetic moment for electrons in bare nanocrystals. This additional magnetic moment manifests itself in a nonzero surface contribution to the linear Zeeman splitting of all quantum size energy levels including the ground 1S electron state. The fitting of the size dependence of the ground state electron g factor in CdSe nanocrystals has allowed us to determine the appropriate surface parameter of the boundary conditions. The structure of the excited electron states is considered in the limits of weak and strong magnetic fields.Comment: 11 pages, 4 figures, submitted to Phys. Rev.

Ballistic conductance in kane type semiconductor quantum wire

The energy spectrum, ballistic conductance of an electron on the surface of a Kane type semiconductor hollow cylinder has been calculated by using the Kane equation with an additional term that takes into account the spin-orbit (SO) interaction. This term, known as Rashba term, occurs for asymmetric quantum wells, where two directions on the normal n are physically nonequivalent. If Rashba spin-orbital interaction is incorporated into energy spectrum, it leads to the emergence of new extrema. We obtained electron energy spectrum, which depends on the sign of the effective spin orbital constant. The energy spectrum of electrons has two branches when the magnetic field does not exist. One of these branches has only one minimum while the other branch has one maximum around k = 0 and two minima. The external magnetic field can control these extrema which occur in the event transport. The results were used to obtain the ballistic conductance at finite temperature of the Kane type hollow cylinder. It has been found that the presence of additional local extremum points in the subband of the electronic spectrum leads to a nonmonotonic dependence of the ballistic conductance of the system on the chemical potential. The g-factor of electrons was observed to depend on Rashba parameter in a linear manner. The effect of finite temperature smears out the sharp steps in the zero-temperature conductance