6,408 research outputs found
Electron-acoustic-phonon scattering and electron relaxation in two-coupled quantum rings
Electron relaxation, induced by acoustic phonons, is studied for coupled
quantum rings in the presence of external fields, both electric and magnetic.
We address the problem of a single electron in vertically coupled GaAs quantum
rings. Electron-phonon interaction is accounted for both deformation potential
and piezoelectric field coupling mechanisms. Depending on the external fields,
the ring radii and the separation between the rings, we show that the two
different couplings have different weights and importance. Significant
oscillations are found in the scattering rates from electron excited states to
the ground state, as a function of either the geometry of the system or the
external fields.Comment: 17 pages, 8 figures, to appear in Journal of Applied Physic
Inelastic Coulomb scattering rate of a multisubband Q1D electron gas
In this work, the Coulomb scattering lifetimes of electrons in two coupled
quantum wires have been studied by calculating the quasiparticle self-energy
within a multisubband model of quasi-one-dimensional (Q1D) electron system. We
consider two strongly coupled quantum wires with two occupied subbands. The
intrasubband and intersubband inelastic scattering rates are caculated for
electrons in different subbands. Contributions of the intrasubband,
intersubband plasmon excitations, as well as the quasiparticle excitations are
investigated. Our results shows that the plasmon exictations of the first
subband are the most important scattering mechanism for electrons in both
subbands.Comment: 9 pages, REVTEX, 2 figure
Hamiltonian of a many-electron system with single-electron and electron-pair states in a two-dimensional periodic potential
Based on the metastable electron-pair energy band in a two-dimensional (2D)
periodic potential obtained previously by Hai and Castelano [J. Phys.: Condens.
Matter 26, 115502 (2014)], we present in this work a Hamiltonian of many
electrons consisting of single electrons and electron pairs in the 2D system.
The electron-pair states are metastable of energies higher than those of the
single-electron states at low electron density. We assume two different
scenarios for the single-electron band. When it is considered as the lowest
conduction band of a crystal, we compare the obtained Hamiltonian with the
phenomenological model Hamiltonian of a boson-fermion mixture proposed by
Friedberg and Lee [Phys. Rev. B 40, 6745 (1989)]. Single-electron-electron-pair
and electron-pair-electron-pair interaction terms appear in our Hamiltonian and
the interaction potentials can be determined from the electron-electron Coulomb
interactions. When we consider the single-electron band as the highest valence
band of a crystal, we show that holes in this valence band are important for
stabilization of the electron-pair states in the system
Anomalous Rashba spin-orbit interaction in InAs/GaSb quantum wells
We investigate theoretically the Rashba spin-orbit interaction in InAs/GaSb
quantum wells(QWs). We find that the Rashba spin-splitting (RSS) depends
sensitively on the thickness of the InAs layer. The RSS exhibits nonlinear
behavior for narrow InAs/GaSb QWs and the oscillating feature for wide
InAs/GaSb QWs. The nonlinear and oscillating behaviors arise from the weakened
and enhanced interband coupling. The RSS also show asymmetric features respect
to the direction of the external electric field.Comment: 3 pages, 4 figures. Appl. Phys. Lett. (in press
Fermionic symmetry-protected topological state in strained graphene
The low-energy physics of graphene is described by relativistic Dirac
fermions with spin and valley degrees of freedom. Mechanical strain can be used
to create a pseudo magnetic field pointing to opposite directions in the two
valleys. We study interacting electrons in graphene exposed to both an external
real magnetic field and a strain-induced pseudo magnetic field. For a certain
ratio between these two fields, it is proposed that a fermionic
symmetry-protected topological state can be realized. The state is
characterized in detail using model wave functions, Chern-Simons field theory,
and numerical calculations. Our paper suggests that graphene with artificial
gauge fields may host a rich set of topological states.Comment: 8 pages, 4 figure
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