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Hopping Models and ac Universality
Author(s) -
Dyre J.C.,
Schrøder Th.B.
Publication year - 2002
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200203)230:1<5::aid-pssb5>3.0.co;2-j
Subject(s) - universality (dynamical systems) , statistical physics , scaling , fracton , physics , dimensionless quantity , renormalization group , mathematics , condensed matter physics , quantum mechanics , mathematical analysis , fractal , geometry
Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA) is the harmonic (fracton) dimension of the diffusion cluster. The temperature scaling of the dimensionless frequency entering into the DCA is discussed. Finally, some open problems regarding ac universality are listed.