Results 1 - 7 of 7
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[en] The behavior of an acoustoelectric current through a three-dimensional quantum microconstriction placed in a longitudinal uniform magnetic field is studied theoretically in the ballistic transport regime. The oscillation periods of the acoustoelectric current are studied in detail as functions of the chemical potential and the magnetic field induction. The temperature effect is taken into account. It is shown that the acoustoelectric current as a function of the chemical potential can exhibit a steplike behavior. The limits for the existence of a steplike structure are determined
[en] The thermopower of asymmetrical quantum wires and constrictions in an arbitrarily directed magnetic field is investigated. An analytic expression convenient for analysing the thermopower is obtained. The oscillations in the thermopower are studied. It is shown that the thermopower as a function of a magnetic field can undergo Aharonov-Bohm and Shubnikov-de Haas oscillations
[en] A dc electric current due to a flow of ultrasonic phonons through a quantum wire containing an isolated point impurity is analyzed theoretically. An explicit expression for the acoustoelectric (AE) current is obtained and its dependence on the chemical potential of the electron gas and the induction of the external magnetic field is investigated. It is shown that a point impurity may lead to a partial or complete destruction of the steplike structure of the AE current as a function of the chemical potential
Abstract—Two-dimensional (2D) semiconductor structures of materials without inversion center (e.g. zinc-blende AIIIBV) possess the zero-field conduction band spin-splitting (Dresselhaus term), which is linear and cubic in wavevector k, that arises from cubic in k splitting in bulk material. At low carrier concentration the cubic term is usually negligible. However, if we will be interested in the following dimensional quantization (in 2D plane) and the character width in this direction is comparable with the width of 2D-structure, then we have to take into account k3-terms as well (even at low concentrations), that after quantization leads to comparable contribution that arises from k-linear term. We propose the general procedure for derivation of Dresselhaus spin-splitting Hamiltonian applicable for any curvilinear 1D-structures. The simple examples for the cases of quantum wire (QWr) and quantum ring (QR) defined in usual -grown 2D-structure are presented.
[en] A new model of a quantum ring defined inside a nanowire is proposed. The one-particle Hamiltonian for electron in -oriented nanowire quantum ring is constructed taking into account both Rashba and Dresselhaus spin-orbit coupling. The energy levels as a function of magnetic field are found using the exact numerical diagonalization. The persistent currents (both charge and spin) are calculated. The specificity of spin-orbit coupling and arising anticrossings in energy spectrum lead to unusual features in persistent current behavior. The variation of magnetic field or carrier concentration by means of gates can lead to pure spin persistent current with the charge current being zero.
[en] The theory of the optical orientation of charge carriers in compensated III-V semiconductors and quantum wells for the case where electrons are excited to the conduction band from Mn-charged acceptor states is presented. It is shown that, in GaAs/AlGaAs quantum wells, the degree of the spin orientation of conduction-band electrons in this excitation scheme can be as high as 85%. This spin-orientation enhancement results from an increase in the heavy-hole contribution to the acceptor state in the vicinity of the defect center rather than from level splitting caused by quantum confinement. It is shown that the degree of circular polarization of the photoluminescence emitted upon the recombination of electrons thermalized at the bottom of the band with holes occupying the acceptor ground state in a quantum well can exceed 70%
[en] Experimental and theoretical piezospectroscopic investigation of A+ centers in GaAs/AlGaAs quantum wells doped with beryllium is presented. Spectra of linearly polarized photoluminescence are studied experimentally depending on applied uniaxial pressure. A model of the A+ center in the quantum well in the presence of uniaxial deformation in the plane of the quantum well has been constructed. Analytical expressions for the level energy, optical transition intensities, and polarization ratio have been obtained. In the framework of the proposed theory, the experimentally observed change in the polarization ratio depending on pressure and the shift of the line maximum towards short waves are explained.