Electric field dependence of specific heat in BaxSr₁₋xTiO₃ ferroelectric perovskites

Abstract

The electric field dependence of the specific heat of an anharmonic BaxSr₁₋xTiO₃ ferroelectric crystal has been calculated in its paraelectric phase from the Silverman-Joseph Hamiltonian augmented with fourth order phonon co-ordinates using double time Green’s functions. The electric field dependent soft mode contribution to the specific heat is described by appropriate Einstein terms. The variation of specific heat with temperature defect and electric field has been discussed. The specific heat decreases with increasing external electric field and increases with increasing temperature, in agreement with previous results. In the vicinity of Curie temperature, the Cochran soft mode is held responsible for the anomalous behaviour of specific heat.