308 research outputs found
Finite size effects in metallic superlattice systems
Clean metallic superlattice systems composed of alternating layers of
superconducting and normal materials are considered, particularly aspects of
the proximity effect as it affects the critical temperature. A simple model is
used to address the question of when a finite--sized system theoretically
approximates well a true infinite superlattice. The methods used in the
analysis afford some tests of the approximation used that the pair amplitude of
the Cooper pairs is constant over a superconducting region. We also use these
methods to construct a model of a single superconducting layer which intends to
incorporate a more realistic form of the pair amplitude than a simple constant.Comment: 16 ReVTeX pages + 12 PostScript figures encoded with uufile
Chapman-Enskog expansion of the Boltzmann equation and its diagrammatic interpretation
We perform a Chapman-Enskog expansion of the Boltzmann equation keeping up to
quadratic contributions. We obtain a generalized nonlinear Kubo formula, and a
set of integral equations which resum ladder and extended ladder diagrams. We
show that these two equations have exactly the same structure, and thus provide
a diagrammatic interpretation of the Chapman-Enskog expansion of the Boltzmann
equation, up to quadratic order.Comment: 5 pages, 2 figures in eps, talk given at XXXI International Symposium
on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. URL
http://ismd31.ccnu.edu.cn
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