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The Czechoslovakian reaction to perestroika : an examination of political and economic change in Czechoslovakia from 1985 to 1990.
Electronic structure basis for the titanic magnetoresistance in WTe
The electronic structure basis of the extremely large magnetoresistance in
layered non-magnetic tungsten ditelluride has been investigated by
angle-resolved photoelectron spectroscopy. Hole and electron pockets of
approximately the same size were found at the Fermi level, suggesting that
carrier compensation should be considered the primary source of the effect. The
material exhibits a highly anisotropic, quasi one-dimensional Fermi surface
from which the pronounced anisotropy of the magnetoresistance follows. A change
in the Fermi surface with temperature was found and a high-density-of-states
band that may take over conduction at higher temperatures and cause the
observed turn-on behavior of the magnetoresistance in WTe was identified
The Ground State of the Pseudogap in Cuprate Superconductors
We present studies of the electronic structure of La2-xBaxCuO4, a system
where the superconductivity is strongly suppressed as static spin and charge
orders or "stripes" develop near the doping level of x=1/8. Using
angle-resolved photoemission and scanning tunneling microscopy, we detect an
energy gap at the Fermi surface with magnitude consistent with d-wave symmetry
and with linear density of states, vanishing only at four nodal points, even
when superconductivity disappears at x=1/8. Thus, the non-superconducting,
"striped" state at x=1/8 is consistent with a phase incoherent d-wave
superconductor whose Cooper pairs form spin/charge ordered structures instead
of becoming superconducting.Comment: This is the author's version of the wor
Application of the scattering rate sum-rule to the interplane optical conductivity of high temperature superconductors: pseudogap and bi-layer effects
We use a recently proposed model of the interplane conductivity of high
temperature superconductors to investigate the `scattering rate sum-rule'
introduced by Basov and co-workers. We present a new derivation of the
sum-rule. The quantal and thermal fluctuations of the order parameter which
have been argued to produce the observed pseudogap behavior are shown to
increase the total integrated `scattering rate' but may either increase or
decrease the `quasiparticle' contribution from frequencies greater than twice
the superconducting gap.Comment: 4 pages, 5 figures, revise
Fine Details of the Nodal Electronic Excitations in BiSrCaCuO
Very high energy resolution photoemission experiments on high quality samples
of optimally doped BiSrCaCuO show new features in the
low-energy electronic excitations. A marked change in the binding energy and
temperature dependence of the near-nodal scattering rates is observed near the
superconducting transition temperature, . The temperature slope of the
scattering rate measured at low energy shows a discontinuity at ~. In the
superconducting state, coherent excitations are found with the scattering rates
showing a cubic dependence on frequency and temperature. The superconducting
gap has a d-wave magnitude with negligible contribution from higher harmonics.
Further, the bi-layer splitting has been found to be finite at the nodal point.Comment: 5 pages, 4 figure
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