100,211 research outputs found
Bosonization for 2D Interacting Fermion Systems: Non-Fermi Liquid Behavior
Non-Fermi liquid behavior is found for the first time in a two-dimensional
(2D) system with non-singular interactions using Haldane's bosonization scheme.
The bosonized system is solved exactly by a generalized Bogoliubov
transformation. The fermion momentum distribution, calculated using a
generalized Mattis-Lieb technique, exhibits a non-universal power law in the
vicinity of the Fermi surface for intermediate interaction strengths.Comment: 13 pages, 2 figures upon request, latex. (to appear in Mod. Phys.
Lett. B
Metallic and semi-metallic <100> silicon nanowires
Silicon nanowires grown along the -direction with a bulk Si core are
studied with density functional calculations. Two surface reconstructions
prevail after exploration of a large fraction of the phase space of nanowire
reconstructions. Despite their energetical equivalence, one of the
reconstructions is found to be strongly metallic while the other one is
semi-metallic. This electronic-structure behavior is dictated by the particular
surface states of each reconstruction. These results imply that doping is not
required in order to obtain good conducting Si nanowires.Comment: 13 pages, 4 figures; Phys. Rev. Lett., in pres
Conformal Symmetry on the Instanton Moduli Space
The conformal symmetry on the instanton moduli space is discussed using the
ADHM construction, where a viewpoint of "homogeneous coordinates" for both the
spacetime and the moduli space turns out to be useful. It is shown that the
conformal algebra closes only up to global gauge transformations, which
generalizes the earlier discussion by Jackiw et al. An interesting
5-dimensional interpretation of the SU(2) single-instanton is also mentioned.Comment: 7 pages, LaTeX, version to appear in J. Phys. A: Math. Ge
Mapping between Hamiltonians with attractive and repulsive potentials on a lattice
Through a simple and exact analytical derivation, we show that for a particle
on a lattice, there is a one-to-one correspondence between the spectra in the
presence of an attractive potential and its repulsive counterpart
. For a Hermitian potential, this result implies that the number of
localized states is the same in both, attractive and repulsive, cases although
these states occur above (below) the band-continnum for the repulsive
(attractive) case. For a \mP\mT-symmetric potential that is odd under parity,
our result implies that in the \mP\mT-unbroken phase, the energy eigenvalues
are symmetric around zero, and that the corresponding eigenfunctions are
closely related to each other.Comment: 6 pages, 1 figur
Phase-sensitive quantum effects in Andreev conductance of the SNS system of metals with macroscopic phase breaking length
The dissipative component of electron transport through the doubly connected
SNS Andreev interferometer indium (S)-aluminium (N)-indium (S) has been
studied. Within helium temperature range, the conductance of the individual
sections of the interferometer exhibits phase-sensitive oscillations of
quantum-interference nature. In the non-domain (normal) state of indium
narrowing adjacent to NS interface, the nonresonance oscillations have been
observed, with the period inversely proportional to the area of the
interferometer orifice. In the domain intermediate state of the narrowing, the
magneto-temperature resistive oscillations appeared, with the period determined
by the coherence length in the magnetic field equal to the critical one. The
oscillating component of resonance form has been observed in the conductance of
the macroscopic N-aluminium part of the system. The phase of the oscillations
appears to be shifted by compared to that of nonresonance oscillations.
We offer an explanation in terms of the contribution into Josephson current
from the coherent quasiparticles with energies of order of the Thouless energy.
The behavior of dissipative transport with temperature has been studied in a
clean normal metal in the vicinity of a single point NS contact.Comment: 9 pages, 7 figures, to be published in Low Temp. Phys., v. 29, No.
12, 200
Magnetic circular dichroism from the impurity band in III-V diluted magnetic semiconductors
The magnetic circular dichroism of III-V diluted magnetic semiconductors,
calculated within a theoretical framework suitable for highly disordered
materials, is shown to be dominated by optical transitions between the bulk
bands and an impurity band formed from magnetic dopant states. The theoretical
framework incorporates real-space Green's functions to properly incorporate
spatial correlations in the disordered conduction band and valence band
electronic structure, and includes extended and localized electronic states on
an equal basis. Our findings reconcile unusual trends in the experimental
magnetic circular dichroism in III-V DMSs with the antiferromagnetic p-d
exchange interaction between a magnetic dopant spin and its host.Comment: 5 pages, 4 figure
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