Antiferromagnetic Ising spin glass

Ising magnetic systems exhibiting re-entrant phase transitions from the antiferromagnetic phase to the non-ergodic mixed phase are considered. The phase diagram in external magnetic field is found. It is shown that the temperature derivative of the sublattice magnetisation is continuous at the re-entrant transition temperature. The reversible magnetic susceptibility in the non-ergodic phase with long-range magnetic order depends slightly on temperature, unlike that in the pure spin glass. It appears that the temperature of the transition into the mixed phase increases with increasing magnetic field.