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We propose a coaxial cylindrical quantum well wire which is composed of layers of a dilute magnetic semiconductor (DMS) and a nonmagnetic semiconductor (NMS). Using effective mass approximation, we present a numerical calculation of the eigenenergies and eigenstates of electrons in the heterostructure. The variation of the spin‐dependent energy levels is influenced by the giant Zeeman splitting and potential energies due to a vector potential for sufficiently low and high magnetic fields, respectively. It is found that crossing and anticrossing behaviors of energy levels can be controlled by the thickness of a NMS layer. The ballistic transport of the structure is also investigated. The ranges of the Fermi energy for obtaining full spin polarization are suggested in this work. [ABSTRACT FROM AUTHOR]

We propose a mechanism for the generation of spin polarization in semiconductor heterostructures with a quantum well and a magnetic impurity layer spatially separated from it. The spin polarization of carriers in a quantum well originates from spin-dependent tunneling recombination at impurity states in the magnetic layer, which is accompanied by a fast linear increase in the degree of circular polarization of photoluminescence from the quantum well. Two situations are theoretically considered. In the first case, resonant tunneling to the spin-split sublevels of the impurity center occurs and spin polarization is caused by different populations of resonance levels in the quantum well for opposite spin projections. In the second, nonresonant case, the spin-split impurity level lies above the occupied states of electrons in the quantum well and plays the role of an intermediate state in the two-stage coherent spin-dependent recombination of an electron from the quantum well and a hole in the impurity layer. The developed theory allows us to explain both qualitatively and quantitatively the kinetics of photoexcited electrons in experiments with photoluminescence with time resolution in Mn-doped InGaAs heterostructures. [ABSTRACT FROM AUTHOR]

In this paper, we study the spin-dependent electron transmission through a quantum well in semiconductor heterostructures with dipole-type oscillation field and homogeneous oscillation field. The numerical evaluations show that Dresselhaus spin-orbit coupling eliminates the spin degeneracy and leads to the splitting of asymmetric Fano-type resonance peaks in the transmissivity. The width of the splitting peaks is found to be highly sensitive to the direction of incident electron. The dipole modulation and the homogeneous modulation is approximately equivalent under certain conditions. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents by the more practical dipole-type oscillation in the experimental setup. [ABSTRACT FROM AUTHOR]

A Hg(Cd)Te insulator heterostructure hosts a two-dimensional electron system that can simulate the physics of Dirac fermions with only a single valley. We investigate the magnetotransport properties of this structure and show that, unlike most two-dimensional crystals with spin and valley coupled levels, the Shubnikov-de Haas oscillations exhibit a high spin polarization in the absence of any valley degree of freedom. This effect can be observed using magnetospectroscopy measurements for quantum well thicknesses corresponding to either the topologically trivial or quantum spin Hall phases. The pseudospin texture of the electrons near the Fermi level is also studied and we show that a tunable pseudospin-polarized quantum Hall liquid can only be observed for thicknesses corresponding to the inverted regime. [ABSTRACT FROM AUTHOR]