9,424 research outputs found
Interplay between different states in heavy fermion physics
Calorimetry experiments under high pressure were used to clarify the
interplay between different states such as superconductivity and
antiferromagnetism in CeRhIn5, spin density wave and large moment
antiferromagnetism in URu2Si2. Evidences are given on the re-entrance of
antiferromagnetism under magnetic field in the superconducting phase of CeRhIn5
up to pc = 2.5 GPa where the Neel temperature will collapse in the absence of
superconductivity. For URu2Si2 measurements up to 10 GPa support strongly the
coexistence of spin density wave and large moment antiferromagnetism at high
pressures.Comment: 6 pages, 9 figures, presented at ICM200
Superconductivity at T_c ~ 14 K in Single Crystalline FeTeSe
Single crystalline FeTeSe with a sharp superconducting
transition at 14 K is synthesized via slow furnace
cooling followed by low-temperature annealing. The effect of annealing on the
chemical and superconducting inhomogeneities is carefully characterized. We
also report resistivity, magnetization, and magneto-optical images of this
crystal. Based on the Bean model, critical current density is estimated to
exceed A/cm below 5 K under zero field. Weak fish-tail
effect is identified at lower temperatures.Comment: 4 pages, 4 figure
Phase Separation in A-site Ordered Perovskite Manganite LaBaMnO Probed by La and Mn NMR
La- and Mn-NMR spectra demonstrate that the ground state of
the A-site ordered perovskite manganite LaBaMnO is a spatial mixture of
the ferromagnetic (FM) and antiferromagnetic (AFI(CE)) regions, which are
assigned to the metallic and the insulating charge ordered state, respectively.
This exotic coexisting state appears below 200 K via a first-order-like
formation of the AFI(CE) state inside the FM one. Mn spin-spin relaxation rate
indicates that the FM region coexisting with the AFI(CE) one in LaBaMnO
is identical to the bulk FM phase of the disordered form
LaBaMnO in spite of the absence of A-site disorder. This
suggests mesoscopic rather than nanoscopic nature of FM region in
LaBaMnO\@.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let
Inverted Hybrid Inflation as a solution to gravitino problems in Gravity Mediation
It was recently found that the decay of inflaton and the SUSY breaking field
produces many gravitinos in the gravity mediation scenario. These discoveries
led to an exclusion of many inflation models such as chaotic, (smooth) hybrid,
topological and new inflation models. Under these circumstances we searched for
a successful inflation model and found that the ``inverted'' hybrid inflation
models can solve the gravitino overproduction problem by their distinctive
shape of the potential. Furthermore, we found that this inflation model
simultaneously can explain the observed baryon asymmetry through the
non-thermal leptogenesis and is consistent with the WMAP results, that is,
and the negligible tensor to scalar ratio.Comment: 23 pages, 2 figures in
Two-band superconductivity featuring different anisotropies in the ternary iron silicide LuFeSi
We report detailed studies of the upper critical field and low-temperature
specific heat in the two-gap superconductor LuFeSi. The
anisotropy of the upper critical field suggests that the active band is
quasi-one-dimensional. Low-temperature specific heat in magnetic fields reveals
that the virtual in the passive band is almost isotropic. These
results strongly indicate that the two bands have two different anisotropies,
similar to the typical two-gap superconductor MgB, and their interplay
may be essential to the two-gap superconductivity in LuFeSi.Comment: 5 pages, 5 figure
Specific heat evidence for two-gap superconductivity in ternary-iron silicide LuFeSi
We report low-temperature specific heat studies on single-crystalline
ternary-iron silicide superconductor LuFeSi with = 6.1 K
down to . We confirm a reduced normalized jump in specific heat at
, and find that the specific heat divided by temperature shows
sudden drop at and goes to zero with further decreasing
temperature. These results indicate the presence of two distinct
superconducting gaps in LuFeSi, similar to a typical two-gap
superconductor MgB. We also report Hall coefficients, band structure
calculation, and the anisotropy of upper critical fields for
LuFeSi, which support the anisotropic multiband nature and
reinforce the existence of two superconducting gaps in
LuFeSi.Comment: 5 pages, 5 figure
Excitation spectrum of Bilayer Quantum Hall Systems
Excitation spectra in bilayer quantum Hall systems at total Landau-level
filling are studied by the Hartree-Fock-Bogoliubov approximation. The
systems have the spin degrees of freedom in addition to the layer degrees of
freedom described in terms of pseudospin. On the excitation spectra from
spin-unpolarized and pseudospin-polarized ground state, this approximation
fully preserves the spin rotational symmetry and thus can give not only
spin-triplet but also spin-singlet excitations systematically. It is also found
that the ground-state properties are well described by this approximation.Comment: 5 pages, 3 figures; conference: EP2DS-1
Electron- and Hole-Doping Effects on -site Ordered NdBaMnO
We have investigated electron- and hole-doping effects on -site ordered
perovskite manganite NdBaMnO, which has the -type (layered)
antiferromagnetic (AFM) ground state. Electrons (holes) are introduced by
partial substitution of Ba (Nd) with Nd (Ba).
Electron-doping generates ferromagnetic (FM) clusters in the -type AFM
matrix. With increasing the electron-doping level, the volume fraction of the
FM phase or the number of the FM clusters is abruptly increasing. In contrast,
the -type AFM phase is robust against the hole-doping, and no FM correlation
is observed in the hole-doped NdBaMnO.Comment: 8 pages, 5 figures, to be published in Journal of the Physical
Society of Japa
Comment on "Isoelectronic Ru substitution at Fe-site in Sm(FeRu)AsOF compound and its effects on structural, superconducting and normal state properties" (arXiv:1004.1978)
Based on the five-orbital model, we derive the reduced impurity scattering
rate in Sm(FeRu)AsOF
from the residual resistivity. At , the transition temperature is
K. For ) the obtained value
of ranges from 1.5 to 2.9, which suggests that the -wave state
cannot survive. We point out that the magnetoresistance frequently gives an
underestimated value of in correlated electron systems.Comment: 2 page
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