Magnetic phase diagram for a random three-dimensional Ising point-dipole lattice

It is shown, within the framework of the generalized mean-field theory, that the ground state of a system of Ising point dipoles randomly filling the sites of a three-dimensional cubic lattice depends on the fraction p of filled sites. For example, a body-centered lattice is ferromagnetic at p > p(c1) approximate to 0.55, a spin glass at p(c1) < p < p(c2) approximate to 0.35, and paramagnetic at p < p(c2). The transition between these states has a percolation nature. The temperature dependences of the magnetization in the ferromagnetic phase and the susceptibility in the paramagnetic phase were determined. The magnetic phase diagram of the system was constructed. (C) 2003 MAIK "Nauka/Interperiodica".