1,847 research outputs found
Superconductivity of the Ternary Boride Li_2Pd_3B Probed by ^{11}B NMR
We report a ^{11}B NMR measurement on the recently discovered superconductor
Li_2Pd_3B. The nuclear spin lattice relaxation rate 1/T_1 shows a well-defined
coherence peak just below T_c (H=1.46 T)=5.7 K, and the spin susceptibility
measured by the Knight shift also decreases below T_c. These results indicate
that the superconductivity is of conventional nature, with an isotropic gap.
Our results also suggest that the -electrons of boron and the d-electrons of
palladium that hybridize with boron -electrons are primarily responsible for
the superconductivity.Comment: 4 pages, 5 figure
Probing the extended non-Fermi liquid regimes of MnSi and Fe
Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe
spans over an unexpectedly broad pressure range, between the critical pressure
p_c and around 2p_c. In order to determine the extension of their NFL regions,
we analyze the evolution of the resistivity rho(T) A(p)T^n at higher pressures.
We find that in MnSi the n=3/2 exponent holds below 4.8 GPa=3 p_c, but it
increases above that pressure. At 7.2 GPa we observe the low temperature Fermi
liquid exponent n=2 whereas for T>1.5 K, n=5/3. Our measurements in Fe show
that the NFL behavior rho T^{5/3} extends at least up to 30.5 GPa, above the
entire superconducting (SC) region. In the studied pressure range, the onset of
the SC transition reduces by a factor 10 down to T_c^onset(30.5 GPa)=0.23 K,
while the A-coefficient diminishes monotonically by around 50%.Comment: 2 pages, 2 figures, Proceedings SCES 200
Finding a Mate With No Social Skills
Sexual reproductive behavior has a necessary social coordination component as
willing and capable partners must both be in the right place at the right time.
While there are many known social behavioral adaptations to support solutions
to this problem, we explore the possibility and likelihood of solutions that
rely only on non-social mechanisms. We find three kinds of social organization
that help solve this social coordination problem (herding, assortative mating,
and natal philopatry) emerge in populations of simulated agents with no social
mechanisms available to support these organizations. We conclude that the
non-social origins of these social organizations around sexual reproduction may
provide the environment for the development of social solutions to the same and
different problems.Comment: 8 pages, 5 figures, GECCO'1
Results of a Search for Paraphotons with Intense X-ray Beams at SPring-8
A search for paraphotons, or hidden U(1) gauge bosons, is performed using an
intense X-ray beamline at SPring--8. "Light Shining through a Wall" technique
is used in this search. No excess of events above background is observed. A
stringent constraint is obtained on the photon--paraphoton mixing angle, for .Comment: 10 pages, 4 figure
Electron-phonon interaction in the t-J model
We derive a t-J model with electron-phonon coupling from the three-band
model, considering modulation of both hopping and Coulomb integrals by phonons.
While the modulation of the hopping integrals dominates, the modulation of the
Coulomb integrals cannot be neglected. The model explains the experimentally
observed anomalous softening of the half-breathing mode upon doping and a
weaker softening of the breathing mode. It is shown that other phonons are not
strongly influenced, and, in particular, the coupling to a buckling mode is not
strong in this model.Comment: 4 pages, RevTeX, 3 eps figures; final version with minor correction
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