Microwave dielectric dispersion in a multiferroic Pb(Fe1/2Nb1/2)O3 thin film

We present the dielectric dispersion in a Pb(Fe1/2Nb1/2)O-3 (PFN) thin film grown on (001) SrTiO3 substrate from 20 MHz to 20 GHz in the temperature range of 270 to 340 K. In the radio frequency region, the hopping charge transport and associated polar nanoregion and/or domain-wall motion contribute to the spectrum. In the microwave region, relaxational dispersion was observed with a dielectric contribution of Delta epsilon approximate to 600 at room temperature having a characteristic frequency (f(m))(0.4) = 9.8 . (T-T-0) Hz, where T-0 is 660 K. It is associated with possible mode-softening behavior, related to the onset of polar nanoregions at T-0. The dielectric permittivity shows similarities with 1-dimensional Ising model behaviour. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3696043]