Europhysics Letters (EPL)
Field Theory for Site-Disordered Spin Glasses
Theo M. Nieuwenhuizen
Abstract
In realistic spin glasses a fraction c of spins is located at random positions. Their couplings are determined by the relative spin positions. For such systems a field theory is formulated. In a certain mean-field limit it generalizes the Sherrington-Kirkpatrick free energy of a random bond spin glass. In general, an infinity of multistate overlaps occurs, as in the diluted random bond spin glass of Viana and Bray. For small c there occurs a percolation transition for short-range exchange and the "concentration scaling" T G ∼ c for RKKY couplings.