29,808 research outputs found
Structure and stability of quasi-two-dimensional boson-fermion mixtures with vortex-antivortex superposed states
We investigate the equilibrium properties of a quasi-two-dimensional
degenerate boson-fermion mixture (DBFM) with a bosonic vortex-antivortex
superposed state (VAVSS) using a quantum-hydrodynamic model. We show that,
depending on the choice of parameters, the DBFM with a VAVSS can exhibit rich
phase structures. For repulsive boson-fermion (BF) interaction, the
Bose-Einstein condensate (BEC) may constitute a petal-shaped "core" inside the
honeycomb-like fermionic component, or a ring-shaped joint "shell" around the
onion-like fermionic cloud, or multiple segregated "islands" embedded in the
disc-shaped Fermi gas. For attractive BF interaction just below the threshold
for collapse, an almost complete mixing between the bosonic and fermionic
components is formed, where the fermionic component tends to mimic a bosonic
VAVSS. The influence of an anharmonic trap on the density distributions of the
DBFM with a bosonic VAVSS is discussed. In addition, a stability region for
different cases of DBFM (without vortex, with a bosonic vortex, and with a
bosonic VAVSS) with specific parameters is given.Comment: 8 pages,5 figure
Continuous topological phase transitions between clean quantum Hall states
Continuous transitions between states with the {\em same} symmetry but
different topological orders are studied. Clean quantum Hall (QH) liquids with
neutral quasiparticles are shown to have such transitions. For clean bilayer
(nnm) states, a continous transition to other QH states (including non-Abelian
states) can be driven by increasing interlayer repulsion/tunneling. The
effective theories describing the critical points at some transitions are
derived.Comment: 4 pages, RevTeX, 2 eps figure
Numerical simulation of the mechanical response during strain path change: application to Zn alloys.
The microstructure-based hardening model (Beyerlein and Tome, 2007), that accounts for the dislocation reversal-related mechanisms and the cut-through effect, is extended to HCP metals. This model, which is embedded in the visco-plastic self-consistent framework, is applied in this work to predict the mechanical response of Zn alloy during strain path change. The predicted mechanical behavior and texture evolution during pre-loading and reloading is in good agreement with experimental observations. The change in hardening behavior after reloading is well reproduced by this model. The contributions of the different mechanisms are also analyzed. (C) 2014 Published by Elsevier Ltd.open1111Nsciescopu
Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2
In layered superconductors, Josephson junctions may be formed within the unit
cell due to sufficiently low interlayer coupling. These intrinsic Josephson
junction (iJJ) systems have attracted considerable interest for their
application potential in quantum computing as well as efficient sources of THz
radiation, closing the famous "THz gap". So far, iJJ have been demonstrated in
single-band, copper-based high-Tc superconductors, mainly in Ba-Sr-Ca-Cu-O.
Here we report clear experimental evidence for iJJ behavior in the iron-based
superconductor (V2Sr4O6)Fe2As2. The intrinsic junctions are identified by
periodic oscillations of the flux flow voltage upon increasing a well aligned
in-plane magnetic field. The periodicity is well explained by commensurability
effects between the Josephson vortex lattice and the crystal structure, which
is a hallmark signature of Josephson vortices confined into iJJ stacks. This
finding adds (V2Sr4O6)Fe2As2 as the first iron-based, multi-band superconductor
to the copper-based iJJ materials of interest for Josephson junction
applications, and in particular novel devices based on multi-band Josephson
coupling may be realized.Comment: Accepted in Nature Physic
Steering far-field spin-dependent splitting of light by inhomogeneous anisotropic media
An inhomogeneous anisotropic medium with specific structure geometry can
apply the tunable spin-dependent geometrical phase to the light passing through
the medium, and thus can be used to steer the spin-dependent splitting (SDS) of
light. In this paper, we exemplify this inference by the q plate, an
inhomogeneous anisotropic medium. It is demonstrated that when a linearly
polarized light beam normally passes through a q plate, k-space SDS first
occurs, and then the real-space SDS in the far-field focal plane of a
converging lens is distinguishable. Interestingly, the SDS, described by the
normalized Stokes parameter S3 shows a multilobe and rotatable splitting
pattern with rotational symmetry. Further, by tailoring the structure geometry
of the q plate and/or the incident polarization angle of light, the lobe number
and the rotation angle both are tunable. Our result suggests that the q plate
can serve as a potential device for manipulating the photon spin states and
enable applications such as in nano-optics and quantum information.Comment: 5 pages, 5 figure
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