Physical properties of a spin model described by an effective Hamiltonian with two kinds of random magnetic bonds

Abstract We report analytical formulae and numerical results for physical properties (magnetization, susceptibility, specific heat) of a spin model with two kinds of random magnetic bonds, in particular near a critical point. This model interpolates between the usual (diluted) Ising and Heisenberg random bond Hamiltonians and allows one to discuss a larger class of new mixed compounds of actual interest.