Defect-mediated relaxation and non-linear susceptibilities of Rochelle salt

TL;DR

This paper extends the Mitsui model to include defect interactions in Rochelle salt, enabling calculation of its non-linear susceptibilities and piezoelectric responses, especially near phase transition temperatures.

Contribution

The study introduces a modified pseudospin model incorporating defect interactions, providing a comprehensive description of Rochelle salt's dynamic susceptibilities and piezoelectric behavior.

Findings

Accurately describes defect-assisted dispersion below 1 kHz

Models susceptibilities near transition temperatures T_C1,2

Predicts non-linear susceptibilities and piezoelectric coefficients

Abstract

The deformable pseudospin Mitsui model is modified in order to take into account interactions of the ordering dipoles of Rochelle salt with dipoles, associated with switchable crystal defects. Using the Glauber-type kinetics of the ordering and defect pseudospins, we calculate the linear, second, and third order dynamic susceptibilities and piezoelectric coefficients of the system. The defect-assisted dispersion of the dynamic characteristics below 1 kHz is described. Behavior of the linear and non-linear susceptibilities close to T_C1,2 is also satisfactorily described by the presented model.