Excitations in randomly diluted antiferromagnets

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Abstract
Results for the zero-temperature spin-wave stiffness, frequency-wavevector response functions and density of states for a randomly diluted, two sub-lattice antiferromagnet on a body-centred cubic lattice are presented for various impurity concentrations. The authors (1972, 73, 75) extend and employ a path type of CPA originally used by Brouers and associates, for studying random electronic systems and later developed by Theumann and Tahir-Kheli (1975) for treating site random ferromagnets. The results are compared with those given by an exact Monte Carlo computer simulation study by Holcomb and Harris (1975). Considering the fact that the authors' is a single-site CPA, the agreement between these results is found to be good. At low impurity concentrations, the authors have evaluated appropriate perturbation theory T-matrices such that all magnetic excitations are removed from non-magnetic sites and find an exact agreement with them. Whenever possible, they have also compared these results with those given by Holcomb's CPA and find the overall quality of the results to be somewhat superior.

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