Anomalous temperature dependence of heat capacity during a cooling-heating cycle in glassy systems

Abstract

Anomalous temperature dependence of heat capacity of glassy systems during a cooling-heating cycle has remained an ill-understood problem for a long time. Most of the features observed in the experimental measurement of the heat capacity of a supercooled liquid are shown here to be adequately explained by a general model. The model that we propose is motivated by the success of landscape paradigm, and describes β relaxation in terms of a collection of two-level systems and conceives α relaxation as a β relaxation mediated cooperative transition in a double-well. The anomalous sharp rise in the heat capacity observed during heating is shown to have a kinetic origin, being caused by delayed energy relaxation due to nonequilibrium effects.