102,133 research outputs found
Superfluid Suppression in d-Wave Superconductors due to Disordered Magnetism
The influence of static magnetic correlations on the temperature-dependent
superfluid density \rho_s(T) is calculated for d-wave superconductors. In
self-consistent calculations, itinerant holes form incommensurate spin density
waves (SDW) which coexist with superconductivity. In the clean limit, the
density of states is gapped, and \rho_s(T << T_c) is exponentially activated.
In inhomogeneously-doped cases, the SDW are disordered and both the density of
states and \rho_s(T) obtain forms indistinguishable from those in dirty but
pure d-wave superconductors, in accordance with experiments. We conclude that
the observed collapse of \rho_s at x\approx 0.35 in underdoped YBCO may
plausibly be attributed to the coexistence of SDW and superconductivity.Comment: 6 pages, 5 figures. Expanded discussio
Comparator for the comparison of two binary numbers Patent
Characteristics of comparator circuits for comparison of binary numbers in information processing syste
On superconducting instability in non-Fermi liquid: scaling approach
The superconducting instability in a non-Fermi liquid in is
considered. For a particular form of the single particle spectral function with
homogeneous scaling it is shown that the pair susceptibility is also a scaling function of
temperature with power defined by . We find three different regimes
depending on the scaling constant. The BCS result is recovered for and it corresponds to a marginal scaling of the coupling constant. For
the superconducting transition happens above some critical
coupling. In the opposite case of for any fixed coupling the
system undergoes a transition at low temperatures. Possible implications for
theories of high- with a superconducting transition driven by the
interlayer Josephson tunneling are discussed. 1 ps file for fig is attached at
the bottom of the tex file.Comment: 10 pages + 1 fig, LA-UR-275
Thermodynamics of an incommensurate quantum crystal
We present a simple theory of the thermodynamics of an incommensurate quantum
solid. The ground state of the solid is assumed to be an incommensurate
crystal, with quantum zero-point vacancies and interstitials and thus a
non-integer number of atoms per unit cell. We show that the low temperature
variation of the net vacancy concentration should be as , and that the
first correction to the specific heat due to this varies as ; these are
quite consistent with experiments on solid He. We also make some
observations about the recent experimental reports of ``supersolidity'' in
solid He that motivate a renewed interest in quantum crystals.Comment: revised, new title, somewhat expande
A Fermi Sea of Heavy Electrons (a Kondo Lattice) is Never a Fermi Liquid
I demonstrate a contradiction which arises if we assume that the Fermi
surface in a heavy electron metal represents a finite jump in occupancy
A time-dependent approach to the numerical solution of the flow field about an axisymmetric vehicle at angle of attack Final report
Three dimensional inviscid flow field analysis for axisymmetric configurations at angle of attac
Channeled propagation of solar particles
Bartley (1966) and McCracken and Ness (1966) identified bundles of interplanetary magnetic field (IMF) lines that differed in direction from the interplanetary field lines in which they were imbedded. These bundles, called filaments differed in direction by as much as several tens of degrees from the surrounding field. The filaments werre first noticed due to the large and sudden change in flow direction of highly anisotropic solar flare protons in the energy range 1 to 13 MeV. Passage of the filaments over the spacecraft required a few hours, implying a diameter for the filaments of approximately 3 x 10 to the 6th power km at a distance of 1 AU from the Sun. In 1968, Jakipii and Parker used Leighton's hypothesis of random walk of magnetic field lines associated with granules and supergranules (1964) to develop a picture of an interplanetary medium composed of a tangle of field lines frozen into the solar wind, but whose feet were carried about by the random motions at the solar surface. Jakipii and Parker noted that using a correlation length of 15,000 km - about the radius of a supergranule - the magnetic structure would be 3 x 10 to the 6th power km in size of the filaments as determined by Bartley and McCracken and Ness. These workers did not find changes in the solar particle intensity, anisotropy ratio or energy spectrum as the spacecraft entered the filament
c-axis transport and phenomenology of the pseudo-gap state in
We measure and analyze the resistivity of
crystals for different doping . We obtain the fraction of carrier
that do not participate to the c-axis
conductivity. All the curves collapse onto a universal curve
when plotted against a reduced temperature
. We find that at the superconducting
transition is doping independent. We also show that a magnetic field up
to 14 T does not affect the degree of localization in the (a,b) planes but
widens the temperature range of the x-scaling by suppressing the
superconducting phase coherence.Comment: 11 pages, 5 figures, submitted to Phys.Rev.
Particle propagation channels in the solar wind
The intensities of low energy solar-interplanetary electrons and ions at 1 AU occasionally change in a square wave manner. The changes may be increases or decreases and they typically have durations of from one hour to a few hours. In some cases these channels are bounded by discontinuities in the interplanetary field and the plasma properties differ from the surrounding solar wind. In one case solar flare particles were confined to a channel of width 3 x 10 to the 6th km at Earth. At the Sun this dimension extrapolates to about 12,000 km, a size comparable to small flares
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