Effect of an InP/In0.53_{0.53}Ga0.47_{0.47}As Interface on Spin-orbit Interaction in In0.52_{0.52}Al0.48_{0.48}As/In0.53_{0.53}Ga0.47_{0.47}As Heterostructures

We report the effect of the insertion of an InP/In$_{0.53}$Ga$_{47}$As Interface on Rashba spin-orbit interaction in In$_{0.52}$Al$_{0.48}$As/In$_{0.53}$Ga$_{0.47}$As quantum wells. A small spin split-off energy in InP produces a very intriguing band lineup in the valence bands in this system. With or without this InP layer above the In$_{0.53}$Ga$_{47}$As well, the overall values of the spin-orbit coupling constant $\alpha$ turned out to be enhanced or diminished for samples with the front- or back-doping position, respectively. These experimental results, using weak antilocalization analysis, are compared with the results of the $\mathbf{k\cdot p}$ theory. The actual conditions of the interfaces and materials should account for the quantitative difference in magnitude between the measurements and calculations.Comment: Submitted for publication; v2 to adjust Eq.6; v3 to correct the figure file name; v4, a revised version accepted for publication in Phys. Rev.

Nonlinear realization of local symmetries of AdS space

Coset methods are used to construct the action describing the dynamics associated with the spontaneous breaking of the local symmetries of AdS_{d+1} space due to the embedding of an AdS_d brane. The resulting action is an SO(2,d) invariant AdS form of the Einstein-Hilbert action, which in addition to the AdS_d gravitational vielbein, also includes a massive vector field localized on the brane. Its long wavelength dynamics is the same as a massive Abelian vector field coupled to gravity in AdS_d space.Comment: 17 page

Gauging Nonlinear Supersymmetry

Coset methods are used to construct the action describing the dynamics associated with the spontaneous breaking of the local supersymmetries. The resulting action is an invariant form of the Einstein-Hilbert action, which in addition to the gravitational vierbein, also includes a massive gravitino field. Invariant interactions with matter and gauge fields are also constructed. The effective Lagrangian describing processes involving the emission or absorption of a single light gravitino is analyzed.Comment: 20 pages, no figure

Focusing of Spin Polarization in Semiconductors by Inhomogeneous Doping

We study the evolution and distribution of non-equilibrium electron spin polarization in n-type semiconductors within the two-component drift-diffusion model in an applied electric field. Propagation of spin-polarized electrons through a boundary between two semiconductor regions with different doping levels is considered. We assume that inhomogeneous spin polarization is created locally and driven through the boundary by the electric field. The electric field distribution and spin polarization distribution are calculated numerically. We show that an initially created narrow region of spin polarization can be further compressed and amplified near the boundary. Since the boundary involves variation of doping but no real interface between two semiconductor materials, no significant spin-polarization loss is expected. The proposed mechanism will be therefore useful in designing new spintronic devices

Superconformal Symmetry, The Supercurrent And Non-BPS Brane Dynamics

The Noether currents associated with the non-linearly realized super-Poincare' symmetries of the Green-Schwarz (Nambu-Goto-Akulov-Volkov) action for a non-BPS p=2 brane embedded in a N=1, D=4 target superspace are constructed. The R symmetry current, the supersymmetry currents, the energy-momentum tensor and the scalar central charge current are shown to be components of a world volume supercurrent. The centrally extended superconformal transformations are realized on the Nambu-Goldstone boson and fermion fields of the non-BPS brane. The superconformal currents form supersymmetry multiplets with the world volume conformal central charge current and special conformal current being the primary components of the supersymmetry multiplets containing all the currents. Correspondingly the superconformal symmetry breaking terms form supersymmetry multiplets the components of which are obtainable as supersymmetry transformations of the primary currents' symmetry breaking terms.Comment: 27 pages, LaTeX, Summary Tables Adde

Self-similar solution of fast magnetic reconnection: Semi-analytic study of inflow region

An evolutionary process of the fast magnetic reconnection in ``free space'' which is free from any influence of outer circumstance has been studied semi-analytically, and a self-similarly expanding solution has been obtained. The semi-analytic solution is consistent with the results of our numerical simulations performed in our previous paper (see Nitta et al. 2001). This semi-analytic study confirms the existence of self-similar growth. On the other hand, the numerical study by time dependent computer simulation clarifies the stability of the self-similar growth with respect to any MHD mode. These results confirm the stable self-similar evolution of the fast magnetic reconnection system.Comment: 15 pages, 7 figure