paper

Griffiths singularity in the random Ising ferromagnet

arXiv:cond-mat/0505233 · doi:10.1007/s10955-005-8079-6

Abstract

The explicit form of the Griffiths singularity in the random ferromagnetic Ising model in external magnetic field is derived. In terms of the continuous random temperature Ginzburg-Landau Hamiltonian it is shown that in the paramagnetic phase away from the critical point the free energy as the function of the external magnetic field h in the limit h -> 0 has the essential singularity of the form (where 1<D<4 is the space dimensionality). It is demonstrated that in terms of the replica formalism this contribution to the free energy comes due to off-perturbative replica instanton excitations.

14 pages, 3 figures

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