Enhancement of dielectric constant and associated coupling of polarizationbehavior in thin film relaxor superlattices

Thin film capacitor structures in which the dielectric is composed of super lattices of the relaxors [0.2Pb(Zn1/3Nb2/3)O-3-0.8BaTiO(3)] and Pb(Mg1/3Nb2 /3)O-3 have been fabricated by pulsed laser deposition. Superlattice wavele ngth (Lambda) was varied between similar to3 and similar to 600 nm, and die lectric properties were investigated as a function of Lambda. Progressive e nhancement of the dielectric constant was observed on decreasing Lambda, an d, in contrast to previous work, this was not associated with the onset of Maxwell-Wagner behavior. Polarization measurements as a function of tempera ture suggested that the observed enhancement in dielectric constant was ass ociated with the onset of a coupled response. The superlattice wavelength ( Lambda =20 nm) at which coupled functional behavior became apparent is comp arable to that found in literature for the onset of coupled structural beha vior (between Lambda =5 nm and Lambda =10 nm). (C) 2001 American Institute of Physics.