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Two-component electron fluid in underdoped high- cuprate superconductors
Evidence from NMR of a two-component spin system in cuprate high-
superconductors is shown to be paralleled by similar evidence from the
electronic entropy so that a two-component quasiparticle fluid is implicated.
We propose that this two-component scenario is restricted to the optimal and
underdoped regimes and arises from the upper and lower branches of the
reconstructed energy-momentum dispersion proposed by Yang, Rice and Zhang (YRZ)
to describe the pseudogap. We calculate the spin susceptibility within the YRZ
formalism and show that the doping and temperature dependence reproduces the
experimental data for the cuprates.Comment: 5 pages, 2 figures, accepted for publication in European Physics
Letter
Evidence for two electronic components in high-temperature superconductivity from NMR
A new analysis of 63Cu and 17O NMR shift data on La1.85Sr0.15CuO4 is reported
that supports earlier work arguing for a two-component description of this
material, but conflicts with the widely held view that the cuprates are a
one-component system. The data are analyzed in terms of two components A and B
with susceptibilities Chi(A), Chi(B), and Chi(AB)=Chi(BA) . We find that above
Tc, Chi(AB) and Chi(BB) are independent of temperature and obtain for the first
time the temperature dependence of all three susceptibilities above Tc as well
as the complete temperature dependence of Chi(AA)+Chi(AB) and of
Chi(AB)+Chi(BB) below Tc. The form of the results agrees with that recently
proposed by Barzykin and Pines.Comment: 14 pages, 4 figure
Dual-fermion approach to the Anderson-Hubbard model
We apply the recently developed dual fermion algorithm for disordered
interacting systems to the Anderson-Hubbard model. This algorithm is compared
with dynamical cluster approximation calculations for a one-dimensional system
to establish the quality of the approximation in comparison with an established
cluster method. We continue with a three-dimensional (3d) system and look at
the antiferromagnetic, Mott and Anderson localization transitions. The dual
fermion approach leads to quantitative as well as qualitative improvement of
the dynamical mean-field results and it allows one to calculate the hysteresis
in the double occupancy in 3d taking into account nonlocal correlations
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