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We have analyzed how the symmetries and the anisotropies of energy dispersions and of the spinor states, within full spin-orbit interaction, form the two independent circular spin polarizations. We also compare how the effects produced by Rashba and Dresselhauss interaction terms act on the structure of the Hilbert space. These aspects are used to envisage a voltage controlled multichannel spin-filtering regime in nonmagnetic diode structures.

We have studied effects of symmetry on spin dependent transport in CdTe-Cd 1-x Mn x Te magnetic tunneling diodes. The tunneling and shot-noise currents may give complementary information on charging processes of the resonant levels. Optimized sample design can explore the exchange induced Zeeman splitting to obtain efficient spin-filters.

The 8 x 8 k.p Kane-Weiler model has been extended to study narrow-gap semiconductor quantum wells in the presence of a magnetic field. It is shown that the study of the inherent symmetry in this Hamiltonian model permits a suitable separation of the solution into two orthogonal Hilbert sub-spaces. The electronic properties are evaluated as function of Kane-Luttinger parameters, magnetic field strength, and Landau level number. The selection rules and anomalies in the conduction Zeeman splitting observed in the interband magneto-optical absorption spectrum are analyzed for the Faraday and Voigt geometry configurations. Due to strong intra- and interband admixtures in narrow-gap materials, spin-flip-like transitions are predicted to occur in the magneto-optical spectrum of HgCdTe/CdTe quantum well solid solutions.

The Zeeman splitting in self-assembled quantum dots (QD) has been studied in the strong confinement regime. The QD is modeled by a cap of spherical symmetry of radius a, and Dirichlet's boundary condition is assumed. Explicit expressions for the wave functions and energy levels when a magnetic field is applied perpendicular to the dot base are derived. Analytical expressions up to the fourth order in the magnetic field (B 4 ) for the energy levels and to the second order (B 2 ) for the wave functions are derived. The magnetic fan plot as a function of a solely universal parameter a = (a/l B ) 2 , where l B is the Landau length, is given.