On the correlation of nonperturbative fluctuations of glass-forming liquids and magnetic glasses

Abstract

Contrary to the established ideas that glasses and glass-forming liquids are homogeneous and isotropic, appreciable structural and compositional heterogeneities are observed in these states. The nature of the heterogeneities in glasses and glass-forming liquids is considered, and the influence of these heterogeneities on the properties of magnetic glasses is examined. Heterophase fluctuations (HPFs), which are nonperturbative disturbances, can play an important role in the thermodynamics of glass-forming liquids, and under certain conditions the liquid has a critical point. The heterogeneities generated in the liquid and glassy states by the HPFs are considered, and the Ginzburg–Landau equations for the HPFs are derived. The order parameter chosen is the fraction of noncrystalline solid-state clusters in the liquid. The correlation length of the order parameter is the characteristic mesoscopic scale of the heterogeneities. The mesoscopic compositional and topological disorder of a glass “spills over” into disorder of its spin system. The phase transitions in the spin system are investigated by well-known approaches with allowance for the mesoscopic heterogeneities. It is shown that correlated domains originating from correlated heterogeneities of the liquid substantially alter the susceptibility and relaxation properties of the paramagnetic state. The phase diagram of a magnetic glass is investigated, and some experimental data are discussed.