Nontrivial dependence of dielectric stiffness and SHG on dc bias in relaxors and dipole glasses

TL;DR

This paper investigates how dielectric stiffness and SHG intensity depend on dc bias in relaxors and dipole glasses, revealing a linear relationship explained by a theory of local polarization instability.

Contribution

It introduces a theoretical explanation for the linear dependence of dielectric and SHG responses on dc bias in relaxors and dipole glasses.

Findings

Linear dependence of dielectric stiffness on dc bias in PMN-PT crystals.

Linear dependence of SHG intensity on dc bias in KTaO3:Li at low Li concentrations.

Theoretical model based on local polarization instability explains these phenomena.

Abstract

Dielectric permittivity and Second Harmonic Generation (SHG) studies in the field-cooled mode show a linear dependence of dielectric stiffness (inverse dielectric permittivity) on dc bias in PMN-PT crystals and SHG intensity in KTaO$_{3}$:Li at small Li concentrations. We explain this unusual result in the framework of a theory of transverse, hydrodynamic-type, instability of local polarization.