arXiv:cond-mat/9505056 · Europhysics Letters (EPL)
Scaling treatment of the random-field Ising model
Robin B. Stinchcombe, E. D Moore, S. L. A. de Queiroz
Abstract
Analytic phenomenological scaling is carried out for the random field Ising model in general dimensions d using a bar geometry. Domain wall configurations and their decorated profiles and associated wandering and other exponents (ζ,γ,δ,μ) are obtained by free-energy minimization. Scaling between different bar widths provides the renormalization group (RG) transformation. Its consequences are i) criticality at h = T = 0 in d ⩽ 2 with correlation length ξ( h , T ) diverging like ξ( h ,0) ∝ h −2/(2 − d ) for d < 2 and ξ( h ,0) ∝ exp [1/( c 1 γ h γ )] for d = 2, where c 1 is a decoration constant; ii) criticality in d = 2 + ε dimensions at T = 0, h * = (ε/2 c 1 ) 1/γ , where ξ ∝ [( s − s *)/ s ] −2ε/γ , s ≡ h γ . Finite-temperature generalizations are outlined. Numerical transfer matrix calculations and results from a ground-state algorithm adapted for strips in d = 2 confirm the ingredients which provide the RG description.