Anomalous Temperature Dependence of Heat Capacity During a Cooling-Heating Cycle in Glassy Systems

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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 βrelaxation in terms of a collection of two-level systems and conceives αrelaxation as a βrelaxation 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.