Search

Using a recently developed spin-dependent variational theory for the heterojunction electronic structure, we investigate the spin-orbit (SO) splitting in InGaAs two dimensional electron gases (2DEGs). We discuss in particular its anisotropy, determined by the relative strength of the Rashba and Dresselhaus SO terms. The envelope function formalism is employed analytically, using the 8-band k·p Kane model for the bulk and spin-dependent variational functions for the Rashba split conduction subbands. The Dresselhaus contribution is included via quasi-degenerate first order perturbation theory and the total spin-splitting at the Fermi level is calculated as a function of the Fermi wave-vector direction and of the 2DEG carrier density. Contrary to what it is usually assumed regarding InGaAs quantum wells, we find significant Dresselhaus contribution and corresponding spin-orbit anisotropy in the conduction subbands. [ABSTRACT FROM AUTHOR]

Controlling quantum coherence in light-matter interaction is a key step for advanced ultra-fast and quantum information technology. We theoretically consider a scheme to realize all-optically induced photonic band gaps based on a standing wave electromagnetically induced transparency configuration which can be implemented with nitrogen-vacancy color centers in diamond. For realistic material parameters the resulting band-gap may be tuned via the coupling field to acquire reflectivities very close to unity and sufficiently large bandwidths. [ABSTRACT FROM AUTHOR]

The spin-orbit splitting or Rashba α parameter at the Fermi energy of 2DEGs in InAlAs/InGaAs heterojunctions is calculated as a function of the electron density, with a variational solution to the multi-band envelope-function model, based on the 8-band Kane model for the bulk. Spin-dependent boundary conditions and mean-field approximation for the electron-electron interaction are used and reasonable good quantitative agreement is obtained with recent Shubnikov-de Haas experimental data. [ABSTRACT FROM AUTHOR]

Very large spin-orbit, or zero-field, spin splittings are predicted for thin GaSb/AlSb symmetric quantum wells (QWs) with the absolute conduction minimum deriving from the L point of the bulk Brillouin zone. The electronic structure calculations performed with an improved tight-binding model and reproduced by a 4×4 kp effective Hamiltonian, including valley mixing and k-linear spin splittings derived from the GaSb bulk, are briefly described and specific results for [100] QWs with large splittings and valley mixing are shown which provide direct insight into L-valley III–V nanostructures. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]