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Identifier uch.physics.phd//1998zambetaki
Title Μελέτη εντοπισμού σε ανισότροπα συστήματα
Alternative Title Study of localization in disordered systems
Author Ζαμπετάκη-Αποστολάκη, Ειρήνη
Thesis advisor Οικονόμου, Ελευθέριος
Abstract In the first part of this work we study the localization in weakly coupled planes and weakly coupled chains both numerically with the transfer matrix method and analytically within the self-consinstent theory CPA+PWA. It is found that the localization critical disorder Wc is independent of the propagating direction and is proportional to t1/4 (t=anisotropy strength) for weakly coupled planes, and to t1/2 for weakly coupled chains. However, the correlation, i, (localization, Lc) length in the extended (localized) side of the transition, can be very different for the two directions. We found that i''=t2i(?) and Lc(?) =tLc'', in agreement with the scaling theory of localization. We discuss how this can possible explain the transport properties of high-Tc materials. In the second part of this work, we study the localization, using the transfer matrix scaling techniques, in a model of randomly coupled chains which contains the basic features of conducting polymers. Our results are compared with mean field theory (MFT) results. The quasi-universality proposed by the MFT, in the sense that our four independent parameters can collapse into two, is generally confirmed, although the shape of the phase diagram is to some extend different, and the dependence of Wc vs J*c (J=hopping matrix element between chains, c=concentration of J) breaks down for large anisotropy.
Language Greek
Issue date 1998-07-01
Date available 1998-12-15
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
  Type of Work--Doctoral theses
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