Phenomenological explanation of spontaneous polarisation and onset ferroelectric Phase transition in RbH2AsO4 (RDA) crystal

Abstract

By applying two-time thermal dependent Zuberav’s statistical, retarded Green function approach and modified earlier simple PLCM model Hamiltonian by adding some extra terms into it, like third-order and fourth-order, phonon anharmonic interactions, direct spin-spin terms, extra spin-lattice terms, and four body interaction terms, for theoretical investigation of thermal dependent spontaneous polarization and ferroelectric phase transition in the first-order phase, of RbH2AsO4crystal. It undergoes a ferroelectric phase transition at 109.9K. With the help of Dyson’s equation in the Mean-Field Approximation (MFA), theoretical formulae are obtained for electrical permittivity, tangent delta, Cochran’s mode frequency, spontaneous polarization, and response function. Model values are fitted for the above physical parameters to obtain variations with temperature. A comparison of theoretical finding has been made with the experimental finding reported by Blinc et al [12], and Zolototrubov et al[8].