Nonlinear dielectric characteristics and domain wall freezing in KH2PO4

Abstract

Nonlinear dielectric constants, epsilon(n)'(real part) and epsilon(n) ''(imaginary part), of higher order harmonic responses(up to n=9) were measured in KH2PO4(KDP) crystal near the domain wall freezing temperature T-f similar or equal to 96K by use of a precision dual phase lock-in amplifier system, The observed dependence of epsilon(n)' and epsilon(n) '' on a.c. field amplitude can be understood in terms of the nonlinear polarization dynamics as due to the domain wall motions characterized by a critical field E-c, a power law exponent a, and phase retardation phi.