5,390 research outputs found
ALKALI-RICH FRAGMENTS IN LL-CHONDRITIC BRECCIAS.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月17日(木) 国立国語研究所 2階講
Development of superconducting correlation at low temperatures in the two-dimensional t-J model
The equal-time pairing correlation function of the two-dimensional t-J model
on a square lattice is studied using a high-temperature expansion method. The
sum of the pairing correlation, its spatial dependence, and the correlation
length are obtained as functions of temperature down to . By
comparison of single-particle contributions in the correlation functions, we
find an effective attractive interaction between quasi-particles in
-wave pairings. It is shown that d-wave correlation grows rapidly
at low temperatures for 0.5 < n < 0.9, with n being the electron density. The
temperature for this growth is roughly scaled by J/2. This is in sharp contrast
to the Hubbard model in a weak or intermediate coupling region, where there is
no numerical evidence of superconductivity.Comment: 4 pages, 5 figure
Phase Diagram and Pairing Symmetry of the Two-Dimensional t-J Model by a Variation Theory
Two-dimensional t-J model is studied by a variational Monte Carlo method,
using Gutzwiller-Jastrow-type wave functions. Various kinds of superconducting
pairing symmetries are compared in order to determine the phase diagram of the
ground state in the full J/t-n plane. Near the half filling where the high
temperature superconductivity is expected, the d_{x^2-y^2} wave pairing state
is always the most stable among various symmetries. The three-site term hardly
changes the phase diagram in this regime. In the low electron density, the
extended s-type wave becomes a quantitatively good state for large J/t,
although the energy gain is small. The Gutzwiller wave function is shown to be
the exact ground state in the low-electron-density limit for the supersymmetric
case (J/t=2).Comment: 13 pages, LaTeX with jpsj.sty etc. Hard copies of 22 figures
available on request. Submitted to J.Phys.Soc.Jp
Transport Properties in Ferromagnetic Josephson Junction between Triplet Superconductors
Charge and spin Josephson currents in a ballistic
superconductor-ferromagnet-superconductor junction with spin-triplet pairing
symmetry are studied using the quasiclassical Eilenberger equation. The gap
vector of superconductors has an arbitrary relative angle with respect to
magnetization of the ferromagnetic layer. We clarify the effects of the
thickness of ferromagnetic layer and magnitude of the magnetization on the
Josephson charge and spin currents. We find that 0-\pi transition can occur
except for the case that the exchange field and d-vector are in nearly
perpendicular configuration. We also show how spin current flows due to
misorientation between the exchange field and d-vector.Comment: 6 pages, 8 figure
Index for Three Dimensional Superconformal Field Theories and Its Applications
We review aspects of superconformal indices in three dimension. Three
dimensional superconformal indices can be exactly computed by using
localization method including monopole contribution, and can be applied to
provide evidences for mirror duality, AdS_4/CFT_3 correspondence and global
symmetry enhancement of strongly coupled gauge theories. After reviewing, we
discuss the possibility of global symmetry enhancement in a finite rank of
gauge group.Comment: 14 pages, Proceedings of the Seventh International Conference Quantum
Theory and Symmetries (QTS-7) in Prague, Czech Republic, August, 2011; v2:
minor modifications, discussion of supersymmetry enhancement of abelian ABJM
theory by using an index were adde
Divergence of the Chaotic Layer Width and Strong Acceleration of the Spatial Chaotic Transport in Periodic Systems Driven by an Adiabatic ac Force
We show for the first time that a {\it weak} perturbation in a Hamiltonian
system may lead to an arbitrarily {\it wide} chaotic layer and {\it fast}
chaotic transport. This {\it generic} effect occurs in any spatially periodic
Hamiltonian system subject to a sufficiently slow ac force. We explain it and
develop an explicit theory for the layer width, verified in simulations.
Chaotic spatial transport as well as applications to the diffusion of particles
on surfaces, threshold devices and others are discussed.Comment: 4 pages including 3 EPS figures, this is an improved version of the
paper (accepted to PRL, 2005
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