320,260 research outputs found
Plasmon spectrum of two-dimensional electron systems with Rashba spin-orbit interaction
The dielectric function and plasmon modes of a two-dimensional electron gas
(2DEG) are studied in single- and double-quantum-well structures with Rashba
spin-orbit interaction (RSOI) in the framework of the random-phase
approximation. The RSOI splits each parabolic energy subband of a 2DEG into two
nonparabolic spin branches and affects the electronic many-body correlation and
dielectric properties of the 2DEG. The influence of the RSOI on the 2DEG
plasmon spectrum in single quantum wells appear mainly in three ways: 1) an
overall frequency lowering due to the energy band deformation; 2) a weak
frequency oscillation stemming from the spin-split energy band; and 3)an
enhancement of the Landau damping as a result of the emerging of the
inter-branch single-particle-excitation spectrum. In double quantum wells, the
above effects are enhanced for the optic plasmon mode but diminished for the
acoustic one.Comment: 7 figure
Parity-locking effect in a strongly-correlated ring
Orbital magnetism in an integrable model of a multichannel ring with
long-ranged electron-electron interactions is investigated. In a noninteracting
multichannel system, the response to an external magnetic flux is the sum of
many diamagnetic and paramagnetic contributions, but we find that for
sufficiently strong correlations, the contributions of all channels add
constructively, leading to a parity (diamagnetic or paramagnetic) which depends
only on the total number of electrons. Numerical results confirm that this
parity-locking effect is robust with respect to subband mixing due to disorder.Comment: part of lecture presented in the conference ``Unconventional quantum
liquids", appearing in Z. Phy
The energy spectrum symmetry of Heisenberg model in Fock space
We prove strictly that one dimension spin 1/2 Heisenberg model has a symmetry
of energy spectrum between its subspace and the subspace of the Fock
space. Our proof is completed by introducing two general quantum operations.
One is a flip operation of spin direction and another is a mirror reflection of
spin sites.Comment: Revising version, 7 preprint pages, no figures; Published version
contains some revisions in Languag
Spin and Orbital Splitting in Ferromagnetic Contacted Single Wall Carbon Nanotube Devices
We observed the coulomb blockade phenomena in ferromagnetic contacting single
wall semiconducting carbon nanotube devices. No obvious Coulomb peaks shift was
observed with existing only the Zeeman splitting at 4K. Combining with other
effects, the ferromagnetic leads prevent the orbital spin states splitting with
magnetic field up to 2 Tesla at 4K. With increasing magnetic field further,
both positive or negative coulomb peaks shift slopes are observed associating
with clockwise and anticlockwise orbital state splitting. The strongly
suppressed/enhanced of the conductance has been observed associating with the
magnetic field induced orbital states splitting/converging
SU(m|n) supersymmetric Calogero-Sutherland model confined in harmonic potential
In this work, we study a continuous quantum system of a mixture of bosons and
fermions with the supersymmetry SU(m|n). The particles are confined in a
harmonic well and interact with each other through the 1/r2 interaction. The
ground state wavefunction is constructed explicitly for the most general
SU(m|n) case, with the ground state energy given explicitly. The full energy
spectrum of excitations in the SU(m|n) model is also equal spaced. In the
limiting case where there are no bosons in the system, our results reduce to
those obtained previously.Comment: 9 pages, preprint of ETH-Lausanne (August 1996
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