18,338 research outputs found
First Results from Dark Matter Search Experiment in the Nokogiriyama Underground Cell
An experiment to search for hypothetical particle dark matter using cryogenic
thermal detector, or bolometer is ongoing. The bolometer consists of eight
pieces of 21 g LiF absorbers and sensitive NTD germanium thermistors attached
to them and is installed in the Nokogiriyama underground cell which is a
shallow depth site ( m w.e.). We report on the results from the first
running for about ten days using this arrayed bolometer system together with
appropriate shieldings and muon veto counters. From the obtained energy spectra
the exclusion limits for the cross section of the elastic neutralino-proton
scattering are derived under commonly accepted astrophysical assumptions. The
sensitivity for the light neutralino with a mass below 5 GeV is improved by
this work.Comment: 8 pages, Revtex, 4 figure
Uniform Mixing of High-Tc Superconductivity and Antiferromagnetism on a Single CuO2 Plane in Hg-based Five-layered Cuprate
We report a site selective Cu-NMR study on under-doped Hg-based five-layered
high- cuprate HgBa2Ca4Cu5Oy with a Tc=72 K. Antiferromagnetism (AF)
has been found to take place at TN=290 K, exhibiting a large antiferromagnetic
moment of 0.67-0.69uB at three inner planes (IP's). This value is comparable to
the values reported for non-doped cuprates, suggesting that the IP may be in a
nearly non-doped regime. Most surprisingly, the AF order is also detected with
M(OP)=0.1uB even at two outer planes (OP's) that are responsible for the onset
of superconductivity (SC). The high-Tc SC at Tc = 72 K can uniformly coexist on
a microscopic level with the AF at OP's. This is the first microscopic evidence
for the uniform mixed phase of AF and SC on a single CuO2 plane in a simple
environment without any vortex lattice and/or stripe order.Comment: 4 pages, 4 figures. To be published in Phys.Rev.Let
Phase Diagram of Spinless Fermions on an Anisotropic Triangular Lattice at Half-filling
The strong coupling phase diagram of the spinless fermions on the anisotropic
triangular lattice at half-filling is presented. The geometry of inter-site
Coulomb interactions rules the phase diagram. Unconventional charge ordered
phases are detected which are the recently reported pinball liquid and the
striped chains. Both are induced by the quantum dynamics out of classical
disordered states and afford extremely correlated metallic states and the
particular domain wall-type of excitations, respectively. The disorder once
killed by the quantum effect revives at the finite temperature, which is
discussed in the terms of the organic -ET.Comment: 4pages 6figure
Doping Dependence of Anisotropic Resistivities in Trilayered Superconductor Bi2Sr2Ca2Cu3O10+delta (Bi-2223)
The doping dependence of the themopower, in-plane resistivity rho_ab(T),
out-of-plane resistivity rho_c(T), and susceptibility has been systematically
measured for high-quality single crystal Bi2Sr2Ca2Cu3O10+delta. We found that
the transition temperature Tc and pseudogap formation temperature T_rho_c*,
below which rho_c shows a typical upturn, do not change from their optimum
values in the "overdoped" region, even though doping actually proceeds. This
suggests that, in overdoped region, the bulk is determined by the always
underdoped inner plane, which have a large superconducting gap, while the
carriers are mostly doped in the outer planes, which have a large phase
stiffness.Comment: 5 pages, 4 figures. to be published in PR
Cu-spin dynamics in the overdoped regime of La_2-x_Sr_x_Cu_1-y_Zn_y_O_4_ probed by muon spin relaxation
Muon-spin-relaxation measurements have been performed for the partially
Zn-substituted La_2-x_Sr_x_Cu_1-y_Zn_y_O_4_ with y=0-0.10 in the overdoped
regime up to x=0.30. In the 3 % Zn-substituted samples up to x=0.27,
exponential-like depolarization of muon spins has been observed at low
temperatures, indicating Zn-induced slowing-down of the Cu-spin fluctuations.
The depolarization rate decreases with increasing x and almost no fast
depolarization of muon spins has been observed for x=0.30 where
superconductivity disappears. The present results suggest that the dynamical
stripe correlations exist in the whole superconducting regime of
La_2-x_Sr_x_CuO_4_ and that there is no quantum critical point at x~0.19.Comment: 6 pages, 5 figure
- …