456 research outputs found
Feynman path-integral approach to the QED3 theory of the pseudogap
In this work the connection between vortex condensation in a d-wave
superconductor and the QED gauge theory of the pseudogap is elucidated. The
approach taken circumvents the use of the standard Franz-Tesanovic gauge
transformation, borrowing ideas from the path-integral analysis of the
Aharonov-Bohm problem. An essential feature of this approach is that
gauge-transformations which are prohibited on a particular multiply-connected
manifold (e.g. a superconductor with vortices) can be successfully performed on
the universal covering space associated with that manifold.Comment: 15 pages, 1 Figure. Int. J. Mod. Phys. B 17, 4509 (2003). Minor
changes from previous versio
The Interacting Impurity Josephson Junction: Variational Wavefunctions and Slave Boson Mean Field Theory
We investigate the Josephson coupling between two superconductors mediated
through an infinite U Anderson impurity, adapting a variational wavefunction
approach which has proved successful for the Kondo model. Unlike the Kondo
problem, however, a crossing of singlet and doublet state energies may be
produced by varying the ratio of Kondo energy to superconducting gap, in
agreement with recent work of Clerk and Ambegaokar. We construct the phase
diagram for the junction and discuss properties of different phases. In
addition, we find the singlet and doublet state energies within a slave boson
mean field approach. We find the slave boson mean field treatment is unable to
account for the level crossing.Comment: 5 pages; 4 encapsulated PostScript figures; submitted to Phys. Rev.
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