50,117 research outputs found
The suppression of superconductivity in Mn substituted MgCNi
We report the effect of doping Mn in the isostructural MgCNiMn
(x = 0-0.05) compounds. Magnetic susceptibility, resistivity,
magneto-resistance, and specific heat studies show evidence of localized
moments and Kondo effect in samples with x0. The rapid suppression of
superconductivity ( -21K/at.% Mn) in these compounds is a consequence of
pair breaking effects due to moment formation on Mn.Comment: 9 figures, Accepted for publication in Physical Review B, Added
reference
Effective Actions for 0+1 Dimensional Scalar QED and its SUSY Generalization at
We compute the effective actions for the 0+1 dimensional scalar field
interacting with an Abelian gauge background, as well as for its supersymmetric
generalization at finite temperature.Comment: 5 pages, Latex fil
Thermal field theory derivation of the source term induced by a fast parton from the quark energy-momentum tensor
I derive the distribution of energy and momentum transmitted from a fast
parton to a medium of thermalized quarks, or the source term, in perturbative
thermal field theory directly from the quark energy-momentum tensor. The fast
parton is coupled to the medium by adding an interaction term to the
Lagrangian. The thermal expectation value of the energy-momentum tensor source
term is then evaluated using standard Feynman rules at finite temperature. It
is found that local excitations, which are important for exciting an observable
Mach cone structure, fall sharply as a function of the energy of the fast
parton. This may have implications for the trigger dependence of
measurements of azimuthal dihadron particle correlations in heavy-ion
collisions. In particular, a conical emission pattern would be less likely to
be observed for increasing trigger . I show that the results presented in
this paper can be generalized to more realistic modeling of fast parton
propagation, such as through a time dependent interaction term, in future
studies.Comment: Version as accepted by Physical Review D. New version has several
clarifications and added references. 5 pages, 3 figure
Supersymmetry and the Chiral Schwinger Model
We have constructed the N=1/2 supersymmetric general Abelian model with
asymmetric chiral couplings. This leads to a N=1/2 supersymmetrization of the
Schwinger model. We show that the supersymmetric general model is plagued with
problems of infrared divergence. Only the supersymmetric chiral Schwinger model
is free from such problems and is dynamically equivalent to the chiral
Schwinger model because of the peculiar structure of the N=1/2 multiplets.Comment: one 9 pages Latex file, one ps file with one figur
Reconstructing the bulk Fermi surface and the superconducting gap properties from Neutron Scattering experiments
We develop an analytical tool to extract bulk electronic properties of
unconventional superconductors through inelastic neutron scattering (INS)
spectra. Since the spin excitation spectrum in the superconducting (SC) state
originates from Bogoliubov quasiparticle scattering associated with Fermi
surface nesting, its energy-momentum relation--the so called `hour-glass'
feature--can be inverted to reveal the Fermi momentum dispersion of the
single-particle spectrum as well as the corresponding SC gap function. The
inversion procedure is analogous to the quasiparticle interference (QPI) effect
in scanning tunneling microscopy (STM). Whereas angle-resolved photoemission
spectroscopy (ARPES) and STM provide surface sensitive information, our
inversion procedure provides bulk electronic properties. The technique is
essentially model independent and can be applied to a wide variety of
materials.Comment: 8 pages, 4 figure
Nonmonotonic superconducting gap in electron-doped PrLaCeCuO: Evidence of coexisting antiferromagnetism and superconductivity?
Recent experiments on PrLaCeCuO observe an anisotropic
spin-correlation gap and a nonmonotonic superconducting (SC) gap, which we
analyze within the framework of a
model with a
pairing interaction including a third harmonic contribution. By
introducing a realistic broadening of the quasiparticle spectrum to reflect
small-angle scattering, our computations explain the experimental observations,
especially the presence of a maximum in the leading edge gap in the vicinity of
the hot-spots. Our analysis suggests that the material behaves like a {\it
two-band} superconductor with the d-wave third harmonic acting as the {\it
interband pairing gap}, and that the anti-ferromagnetic (AFM) and SC orders
co-exist in a uniform phase
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