T. NATTERMANN
Institute for Theoretical Physics, University of Cologne, Z¨ulpicherstr. 77, 50937 Cologne, Germany
Abstract:
A review is given on some recent developments in the theory of the Ising model in a random field.
This model is a good representation of a large number of impure materials. After a short repetition
of earlier arguments, which prove the absence of ferromagnetic order in d ≤ 2 space dimensions for
uncorrelated random fields, we consider different random field correlations and in particular the
generation of uncorrelated from anti-correlated random fields by thermal fluctuations. In discussing
the phase transition, we consider the transition to be characterized by a divergent correlation
length and compare the critical exponents obtained from various methods (real space RNG, Monte
Carlo calculations, weighted mean field theory etc.). The ferromagnetic transition is believed to
be preceded by a spin glass transition which manifests itself by replica symmetry breaking. In
the discussion of dynamical properties, we concentrate mainly on the zero temperature depinning
transition of a domain wall, which represents a critical point far from equilibrium with new scaling
relations and critical exponents.
To download the article click on the link below:
https://arxiv.org/pdf/cond-mat/9705295.pdf
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