Metastable states in disordered Ising magnets in mean-field approximation

The mechanism of appearance of exponentially large number of metastable states in magnetic phases of disordered Ising magnets with short-range random exchange is suggested. It is based on the assumption that transitions into inhomogeneous magnetic phases results from the condensation of macroscopically large number of sparse delocalized modes near the localization threshold. The properties of metastable states in random magnets with zero ground state magnetization (dilute antiferromagnet, binary spin glass, dilute ferromagnet with dipole interaction) has been obtained in framework of this mechanism using variant of mean-field approximation. The relations between the characteristics of slow nonequilibrium processes in magnetic phases (such as hysteresis loop form, thermo-remainent and isothermal remainent magnetizations, field-cooled and zero-field-cooled thermodynamic quantities) and thermodynamic parameters of metastable states are established.