1,265,368 research outputs found
Anomalous physical properties of underdoped weak-ferromagnetic superconductor RuSrEuCuO
Similar to the optimal-doped, weak-ferromagnetic (WFM induced by canted
antiferromagnetism, T = 131 K) and superconducting (T = 56 K)
RuSrGdCuO, the underdoped RuSrEuCuO
(T = 133 K, T = 36 K) also exhibited a spontaneous vortex state
(SVS) between 16 K and 36 K. The low field (20 G) superconducting
hysteresis loop indicates a weak and narrow Meissner state region of average
lower critical field B(T) = B(0)[1 -
(T/T)], with B(0) = 7 G and T = 16 K. The
vortex melting transition (T = 21 K) below T obtained from
the broad resistivity drop and the onset of diamagnetic signal indicates a
vortex liquid region due to the coexistence and interplay between
superconductivity and WFM order. No visible jump in specific heat was observed
near T for Eu- and Gd-compound. This is not surprising, since the
electronic specific heat is easily overshadowed by the large phonon and
weak-ferromagnetic contributions. Furthermore, a broad resistivity transition
due to low vortex melting temperature would also lead to a correspondingly
reduced height of any specific heat jump. Finally, with the baseline from the
nonmagnetic Eu-compound, specific heat data analysis confirms the magnetic
entropy associated with antiferromagnetic ordering of Gd (J = S = 7/2)
at 2.5 K to be close to ln8 as expected.Comment: 7 figure
Toward Five-dimensional Core-collapse Supernova Simulations
The computational difficulty of six-dimensional neutrino radiation
hydrodynamics has spawned a variety of approximations, provoking a long history
of uncertainty in the core-collapse supernova explosion mechanism. Under the
auspices of the Terascale Supernova Initiative, we are honoring the physical
complexity of supernovae by meeting the computational challenge head-on,
undertaking the development of a new adaptive mesh refinement code for
self-gravitating, six-dimensional neutrino radiation magnetohydrodynamics. This
code--called {\em GenASiS,} for {\em Gen}eral {\em A}strophysical {\em
Si}mulation {\em S}ystem--is designed for modularity and extensibility of the
physics. Presently in use or under development are capabilities for Newtonian
self-gravity, Newtonian and special relativistic magnetohydrodynamics (with
`realistic' equation of state), and special relativistic energy- and
angle-dependent neutrino transport--including full treatment of the energy and
angle dependence of scattering and pair interactions.Comment: 5 pages. Proceedings of SciDAC 2005, Scientific Discovery through
Advanced Computing, San Francisco, CA, 26-30 June 200
Compact and Broadband Microstrip-Line-Fed Modified Rhombus Slot Antenna
The printed microstrip-line-fed broadband rhombus slot antenna is investigated in this paper. With the use of the offset microstrip feed line and the corner-truncated protruded ground plane, the bandwidth enhancement and the slot size reduction for the proposed slot antenna can be obtained. The experimental results demonstrate that the impedance bandwidth for 10 dB return loss reaches 5210 MHz (108.2%, 2210-7420 MHz), which is about 2.67 times of a conventional microstrip-line-fed rhombus slot antenna. This bandwidth can provide with the wireless communication services operating in wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) bands. Under the use of the protruded ground plane, the slot size can be reduced by about 52%. Details of simulated and measured results are presented and discussed
Interactions between Octet Baryons in the SU_6 Quark model
The baryon-baryon interactions for the complete baryon octet (B_8) are
investigated in a unified framework of the resonating-group method, in which
the spin-flavor SU_6 quark-model wave functions are employed. Model parameters
are determined to reproduce properties of the nucleon-nucleon system and the
low-energy cross section data for the hyperon-nucleon interaction. We then
proceed to explore B_8 B_8 interactions in the strangeness S=-2, -3 and -4
sectors. The S-wave phase-shift behavior and total cross sections are
systematically understood by 1) the spin-flavor SU_6 symmetry, 2) the special
role of the pion exchange, and 3) the flavor symmetry breaking.Comment: 11 pages, 6 figures, submitted to Phys. Rev. C (Rapid Communication
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