Magnetic field effects on a classical anisotropic spin-glass model

The simple model of a classical spin-glass proposed by van Hemmen 1] is extended to the case of a generalS Ising spin and anisotropy energy. Due to its simplicity, the model is amenable to an exact solution and in the case of spin-1 the phase diagram is similar to that of the Sherrington-Kirkpatrick model. ForS=1 and for certain values of the anisotropy the phase diagram in the (H-T) plane shows continuous and discontinuous transitions, a critical point within the condensed phase, and a field-induced mixed phase in addition to the paramagnetic and spin-glass phases.Work partially supported by CNPq and FINEP (Brazilian Agencies). Part of this work was presented at the International Conference of Magnetism, San Francisco, 1985