14,297 research outputs found
Radiation-induced magnetoresistance oscillation in a two-dimensional electron gas in Faraday geometry
Microwave-radiation induced giant magnetoresistance oscillations recently
discovered in high-mobility two-dimensional electron systems in a magnetic
field, are analyzed theoretically. Multiphoton-assisted impurity scatterings
are shown to be the primary origin of the oscillation. Based on a model which
considers the interaction of electrons with the electromagnetic fields in
Faraday geometry, we are able not only to reproduce the correct period, phase
and the negative resistivity of the main oscillation, but also to obtain
secondary peaks and additional maxima and minima in the resistivity curve, some
of which were already observed in the experiments.Comment: 4 pages, 1 figure, revised version to be published in Phys. Rev. Let
Interaction induced topological phase transition in Bernevig-Hughes-Zhang model
We study interaction induced topological phase transition in
Bernevig-Hughes-Zhang model. Topological nature of the phase transition is
revealed by directly calculating the Z2 index of the interacting system from
the single-particle Green's function. The interacting Z2 index is also
consistently checked through the edge spectra. Combined with ab initio methods,
present approach is a useful tool searching for correlated topological
insulating materials from the first-principle point of view.Comment: 4.5 pages, 4 figures, reference adde
Linear magnetoresistance on the topological surface
A positive, non-saturating and dominantly linear magnetoresistance is
demonstrated to occur in the surface state of a topological insulator having a
wavevector-linear energy dispersion together with a finite positive Zeeman
energy splitting. This linear magnetoresistance shows up within quite wide
magnetic-field range in a spatially homogenous system of high carrier density
and low mobility in which the conduction electrons are in extended states and
spread over many smeared Landau levels, and is robust against increasing
temperature, in agreement with recent experimental findings in BiSe
nanoribbons.Comment: 7 pages, 4 figure
Pole expansion of self-energy and interaction effect on topological insulators
We study effect of interactions on time-reversal-invariant topological
insulators. Their topological indices are expressed by interacting Green's
functions. Under the local self-energy approximation, we connect topological
index and surface states of an interacting system to an auxiliary
noninteracting system, whose Hamiltonian is related to the pole-expansions of
the local self-energy. This finding greatly simplifies the calculation of
interacting topological indices and gives an noninteracting pictorial
description of interaction driven topological phase transitions. Our results
also bridge studies of the correlated topological insulating materials with the
practical dynamical-mean-field-theory calculations.Comment: 4.2 pages, 3 figures, reference added, typos correcte
Interaction-induced anomalous transport behavior in one dimensional optical lattice
The non-equilibrium dynamics of spin impurity atoms in a strongly interacting
one-dimensional (1D) Bose gas under the gravity field is studied. We show that
due to the non-equilibrium preparation of the initial state as well as the
interaction between the impurity atoms and other bosons, a counterintuitive
phenomenon may emerge: the impurity atoms could propagate upwards automatically
in the gravity field . The effects of the strength of interaction, the gradient
of the gravity field, as well as the different configurations of the initial
state are investigated by studying the time-dependent evolution of the 1D
strongly interacting bosonic system using time-evolving block decimation (TEBD)
method. A profound connection between this counterintuitive phenomenon and the
repulsive bound pair is also revealed.Comment: 4.1 page
Universal Boundary Entropies in Conformal Field Theory: A Quantum Monte Carlo Study
Recently, entropy corrections on nonorientable manifolds such as the Klein
bottle are proposed as a universal characterization of critical systems with an
emergent conformal field theory (CFT). We show that entropy correction on the
Klein bottle can be interpreted as a boundary effect via transforming the Klein
bottle into an orientable manifold with nonlocal boundary interactions. The
interpretation reveals the conceptual connection of the Klein bottle entropy
with the celebrated Affleck-Ludwig entropy in boundary CFT. We propose a
generic scheme to extract these universal boundary entropies from quantum Monte
Carlo calculation of partition function ratios in lattice models. Our numerical
results on the Affleck-Ludwig entropy and Klein bottle entropy for the
-state quantum Potts chains with show excellent agreement with the
CFT predictions. For the quantum Potts chain with , the Klein bottle
entropy slightly deviates from the CFT prediction, which is possibly due to
marginally irrelevant terms in the low-energy effective theory.Comment: 10 pages, 4 figures. Published versio
Magnetism of Cold Fermionic Atoms on p-Band of an Optical Lattice
We carry out \textit{ab initio} study of ground state phase diagram of
spin-1/2 cold fermionic atoms within two-fold degenerate -band of an
anisotropic optical lattice. Using the Gutzwiller variational approach, we show
that a robust ferromagnetic phase exists for a vast range of band fillings and
interacting strengths. The ground state crosses over from spin density wave
state to spin-1 Neel state at half filling. Additional harmonic trap will
induce spatial separation of varies phases. We also discuss several relevant
observable consequences and detection methods. Experimental test of the results
reported here may shed some light on the long-standing issue of itinerant
ferromagnetism.Comment: 5 pages, 4 figure
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