3,258 research outputs found
Enhanced Pairing in the "Checkerboard" Hubbard Ladder
We study signatures of superconductivity in a 2--leg "checkerboard" Hubbard
ladder model, defined as a one--dimensional (period 2) array of square
plaquettes with an intra-plaquette hopping and inter-plaquette hopping
, using the density matrix renormalization group method. The highest
pairing scale (characterized by the spin gap or the pair binding energy,
extrapolated to the thermodynamic limit) is found for doping levels close to
half filling, and . Other forms of modulated
hopping parameters, with periods of either 1 or 3 lattice constants, are also
found to enhance pairing relative to the uniform two--leg ladder, although to a
lesser degree. A calculation of the phase stiffness of the ladder reveals that
in the regime with the strongest pairing, the energy scale associated with
phase ordering is comparable to the pairing scale.Comment: 9 pages, 9 figures; Journal reference adde
Transport in Two Dimensional Electronic Micro-emulsions
In two dimensional electron systems with Coulomb or dipolar interactions, a
direct transition, whether first or second order, from a liquid to a
crystalline state is forbidden. As a result, between these phases there must be
other (microemulsion) phases which can be viewed as a meso-scale mixture of the
liquid and crystalline phases. We investigate the transport properties of these
new electronic phases and present arguments that they are responsible for the
various transport anomalies that have been seen in experiments on the strongly
correlated 2DEG in high mobility semiconductor devices with low electron
densities
Quasiparticle scattering and local density of states in graphite
We determine the effect of quasiparticle interference on the spatial
variations of the local density of states (LDOS) in graphite in the
neighborhood of an isolated impurity. A number of characteristic behaviors of
interference are identified in the Fourier transformed spectrum. A comparison
between our results and scanning tunneling microscopy (STM) experiments could
provide a critical test of the range (of energy) of applicability of the Fermi
liquid description of graphite, where some evidence of the breakdown of Fermi
liquid theory has recently been discussed. Moreover, given the similarity
between the band structures of graphite and that of nodal quasiparticles in a
d-wave superconductor, a comparison between results in the two materials is
useful for understanding the physics of the cuprates.Comment: 5 pages, 4 figures, RevTex
High Temperature Superconductivity: Ineluctable Complexity
The discovery of charge-density-wave order in the high-temperature
superconductor YBaCuO places charge order centre stage with
superconductivity, suggesting they they are intertwined rather than competing.Comment: 3 pages, 1 figure, 19 references; News & Views article for Nature
Physic
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