1,510 research outputs found
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
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
Hidden quasi one-dimensional superconductivity in SrRuO
Using an asymptotically exact weak coupling analysis of a multi-orbital
Hubbard model of the electronic structure of \SRO, we show that the interplay
between spin and charge fluctuations leads unequivocally to triplet pairing
which originates in the quasi-one dimensional bands. The resulting
superconducting state spontaneously breaks time-reversal symmetry and is of the
form with sharp gap minima and a d-vector
that is only {\it weakly} pinned. The supercondutor is topologically {\it
trivial} and hence lacks robust chiral Majorana fermion modes along the
boundary. The absence of topologically protected edge modes could explain the
surprising absence of experimentally detectable edge currents in this system.Comment: 5 pages, 3 figure
Local Electronic Structure and High Temperature Superconductivity
It is argued that a new mechanism and many-body theory of superconductivity
are required for doped correlated insulators. Here we review the essential
features of and the experimental support for such a theory, in which the
physics is driven by the kinetic energy.Comment: 8 Pages Latex. For the Proceedings of HTS99, Miami, FL, Jan. 199
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