8,925 research outputs found
Gap Symmetry an Thermal Conductivity in Nodal Superconductors
There are now many nodal superconductors in heavy fermion (HF) systems,
charge conjugated organic metals, high Tc cuprates and ruthenates. On the other
hand only few of them have a well established gap function. We present here a
study of the angular dependent thermal conductivity in the vortex state of some
of the nodal superconductors. We hope it will help to identify the nodal
directions in the gap function of UPd_2Al_3, UNi_2Al_3, UBe_13 and URu_2Si_2.Comment: 4 pages, 5 figure
Nonlinear response and scaling law in the vortex state of d-wave superconductors
We study the field dependence of the quasi-particle density of states, the
thermodynamics and the transport properties in the vortex state of d-wave
superconductors when a magnetic field is applied perpendicular to the
conducting plane, specially for the low field and the low temperature compared
to the upper critical field and transition temperature, respectively, and . Both the superfluid density and the spin
susceptibility exhibit the characteristic -field dependence, while
the nuclear spin lattice relaxation rate T and the thermal
conductivity are linear in field . With increasing temperature, these
quantities exhibit the scaling behavior in . The present theory
applies to 2D -wave superconductor as well; a possible candidate of the
superconductivity in SrRuO.Comment: 11 pages, 4 figure
Gap Symmetry of Superconductivity in UPd2Al3
The angle dependent thermal conductivity of the heavy-fermion superconductor
UPdAl in the vortex state was recently measured by Watanabe et al. Here
we analyze this data from two perspectives: universal heat conduction and the
angle-dependence. We conclude that the superconducting gap function
in UPdAl has horizontal nodes and is given by
, with .Comment: 8 pages, 4 figures, improved figures in replacemen
Novel vortex lattice transition in d-wave superconductors
We study the vortex state in a magnetic field parallel to the axis in the
framework of the extended Ginzburg Landau equation. We find the vortex acquires
a fourfold modulation proportional to where is the angle
makes with the -axis. This term gives rise to an attractive
interaction between two vortices when they are aligned parallel to or
. We predict the first order vortex lattice transition at
from triangular into the square lattice
tilted by from the axis. This gives the critical field
a few Tesla for YBCO and Bi2212 monocrystals at low temperatures ().Comment: 6 pages, 4 figure
Gap Structure of the Spin-Triplet Superconductor Sr2RuO4 Determined from the Field-Orientation Dependence of Specific Heat
We report the field-orientation dependent specific heat of the spin-triplet
superconductor Sr2RuO4 under the magnetic field aligned parallel to the RuO2
planes with high accuracy. Below about 0.3 K, striking 4-fold oscillations of
the density of states reflecting the superconducting gap structure have been
resolved for the first time. We also obtained strong evidence of multi-band
superconductivity and concluded that the superconducting gap in the active
band, responsible for the superconducting instability, is modulated with a
minimum along the [100] direction.Comment: 4 pages, 4 figure
Low-lying excitations around a single vortex in a d-wave superconductor
A full quantum-mechanical treatment of the Bogoliubov-de Gennes equation for
a single vortex in a d-wave superconductor is presented. First, we find
low-energy states extended in four diagonal directions, which have no
counterpart in a vortex of s-wave superconductors. The four-fold symmetry is
due to 'quantum effect', which is enhanced when is small. Second,
for , a peak with a large energy gap is
found in the density of states, which is due to the formation of the lowest
bound states.Comment: 7pages, Revte
Thermal conductivity in B- and C- phase of UPt_3
Although the superconductivity in UPt_3 is one of the most well studied,
there are still lingering questions about the nodal directions in the B and C
phase in the presence of a magnetic field. Limiting ourselves to the low
temperature regime (T<<Delta(0)), we study the magnetothermal conductivity with
in semiclassical approximation using Volovik's approach. The angular dependence
of the magnetothermal conductivity for an arbitrary field direction should
clarify the nodal structure in UPt_3.Comment: 4 pages, 5 figure
Laboratory evaluation of a rapid IgG4 antibody test (BLF Rapid™) for bancroftian filariasis
At the end phase of the Global Programme to Eliminate Lymphatic Filariasis, antibody testing may have a role in decision-making for bancroftian filariasis–endemic areas. This study evaluated the diagnostic performance of BLF Rapid ™ , a prototype immunochromatographic IgG4-based test using BmSXP recombinant protein, for detection of bancroftian filariasis. The test was evaluated using 258 serum samples, comprising 96 samples tested at Universiti Sains Malaysia (in-house) and 162 samples tested independently at three international laboratories in the USA and India, and two laboratories in Malaysia. The independent testing involved 99 samples from Wuchereria bancrofti microfilaria or antigen positive individuals and 63 samples from people who were healthy or had other infections. The in-house evaluation showed 100% diagnostic sensitivity and specificity. The independent evaluations showed a diagnostic sensitivity of 84–100% and 100% specificity (excluding non-lymphatic filarial infections). BLF Rapid has potential as a surveillance diagnostic tool to make “Transmission Assessment Survey”–stopping decisions and conduct post-elimination surveillance
Magnetization reversal in Kagome artificial spin ice studied by first-order reversal curves
Magnetization reversal of interconnected Kagome artificial spin ice was
studied by the first-order reversal curve (FORC) technique based on the
magneto-optical Kerr effect and magnetoresistance measurements. The
magnetization reversal exhibits a distinct six-fold symmetry with the external
field orientation. When the field is parallel to one of the nano-bar branches,
the domain nucleation/propagation and annihilation processes sensitively depend
on the field cycling history and the maximum field applied. When the field is
nearly perpendicular to one of the branches, the FORC measurement reveals the
magnetic interaction between the Dirac strings and orthogonal branches during
the magnetization reversal process. Our results demonstrate that the FORC
approach provides a comprehensive framework for understanding the magnetic
interaction in the magnetization reversal processes of spin-frustrated systems
- …