61,955 research outputs found
Anomalous Nernst Effect in the Vortex-Liquid Phase of High-Temperature Superconductors by Layer Decoupling
Linear diamagnetism is predicted in the vortex-liquid phase of layered
superconductors at temperatures just below the mean-field phase transition on
the basis of a high-temperature analysis of the corresponding frustrated XY
model. The diamagnetic susceptibility, and the Nernst signal by implication, is
found to vanish with temperature as (T_c0 - T)^3 in the vicinity of the
meanfield transition at T_c0. Quantitative agreement with recent experimental
observations of a diamagnetic signal in the vortex-liquid phase of
high-temperature superconductors is obtained.Comment: 8 pages, 3 figure
Fermion Analogy for Layered Superconducting Films in Parallel Magnetic Field
The equivalence between the Lawrence-Doniach model for films of extreme
type-II layered superconductors and a generalization of the back-scattering
model for spin-1/2 electrons in one dimension is demonstrated. This fermion
analogy is then exploited to obtain an anomalous tail for
the parallel equilibrium magnetization of the minimal double layer case in the
limit of high parallel magnetic fields for temperatures in the
critical regime.Comment: 11 pages of plain TeX, 1 postscript figur
Layered XY-Models, Anyon Superconductors, and Spin-Liquids
The partition function of the double-layer model in the (dual) Villain
form is computed exactly in the limit of weak coupling between layers. Both
layers are found to be locked together through the
Berezinskii-Kosterlitz-Thouless transition, while they become decoupled well
inside the normal phase. These results are recovered in the general case of a
finite number of such layers. When re-interpreted in terms of the dual problems
of lattice anyon superconductivity and of spin-liquids, they also indicate that
the essential nature of the transition into the normal state found in two
dimensions persists in the case of a finite number of weakly coupled layers.Comment: 10 pgs, TeX, LA-UR-94-394
Area Littlewood-Paley functions associated with Hermite and Laguerre operators
In this paper we study Lp-boundedness properties for area Littlewood-Paley
functions associated with heat semigroups for Hermite and Laguerre operator
Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy
Stripe domains are studied in perpendicular magnetic anisotropy films
nanostructured with a periodic thickness modulation that induces the lateral
modulation of both stripe periods and inplane magnetization. The resulting
system is the 2D equivalent of a strained superlattice with properties
controlled by interfacial misfit strain within the magnetic stripe structure
and shape anisotropy. This allows us to observe, experimentally for the first
time, the continuous structural transformation of a grain boundary in this 2D
magnetic crystal in the whole angular range. The magnetization reversal process
can be tailored through the effect of misfit strain due to the coupling between
disclinations in the magnetic stripe pattern and domain walls in the in-plane
magnetization configuration
Berezinskii-Kosterlitz-Thouless Transition in Spin-Charge Separated Superconductor
A model for spin-charge separated superconductivity in two dimensions is
introduced where the phases of the spinon and holon order parameters couple
gauge-invariantly to a statistical gauge-field representing chiral
spin-fluctuations. The model is analyzed in the continuum limit and in the
low-temperature limit. In both cases we find that physical electronic phase
correlations show a superconducting-normal phase transition of the
Berezinskii-Kosterlitz-Thouless type, while statistical gauge-field excitations
are found to be strictly gapless. The normal-to-superconductor phase boundary
for this model is also obtained as a function of carrier density, where we find
that its shape compares favorably with that of the experimentally observed
phase diagram for the oxide superconductors.Comment: 35 pages, TeX, CSLA-P-93-
Properties of the predicted super-deformed band in ^{32}S
Properties like the excitation energy with respect to the ground state,
moments of inertia, B(E2) transition probabilities and stability against
quadrupole fluctuations at low spin of the predicted superdeformed band of
^{32}S are studied with the Gogny force D1S using the angular momentum
projected generator coordinate method for the axially symmetric quadrupole
moment. The Self Consistent Cranking method is also used to describe the
superdeformed rotational band. In addition, properties of some collective
normal deformed states are discussed.Comment: 7 pages, 3 figure
A non-Markovian optical signature for detecting entanglement in coupled excitonic qubits
We identify an optical signature for detecting entanglement in experimental
nanostructure systems comprising coupled excitonic qubits. This signature owes
its strength to non-Markovian dynamical effects in the second-order temporal
coherence function of the emitted radiation. We calculate autocorrelation and
cross-correlation functions for both selective and collective light excitation,
and prove that the coherence properties of the emitted light do indeed carry
information about the entanglement of the initial multi-qubit state.
We also show that this signature can survive in the presence of a noisy
environment.Comment: 4 pages, 4 color figures. Minor changes. Accepted version to be
published in Europhysics Letter
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