Europhys. Lett.
Volume 71, Number 1, July 2005
Page(s) 124 - 130
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 June 2005
Europhys. Lett., 71 (1), pp. 124-130 (2005)
DOI: 10.1209/epl/i2005-10056-8

Poling effect on distribution of quenched random fields in a uniaxial relaxor ferroelectric

M. I. Marqués and C. Aragó

Departamento de Física de Materiales C-IV, Universidad Autónoma de Madrid 28049 Madrid, Spain

received 22 February 2005; accepted 2 May 2005
published online 1 June 2005

The frequency dependence of the dielectric permittivity's maximum has been studied for poled and unpoled doped relaxor strontium barium niobate $\chem{Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}}$: $\chem{Cr^{3+}}$ (SBN-61:$\chem{Cr}$). In both cases the maximum found is broad and the frequency dispersion is strong. The present view of random fields compensation in the unpoled sample is not suitable for explaining this experimental result. We propose a new mechanism where the dispersion of quenched random electric fields, affecting the nanodomains, is minimized after poling. We test our proposal by numerical simulations on a random field Ising model. Results obtained are in agreement with the polarization's measurements presented by Granzow et al. (Phys. Rev. Lett. 92 (2004) 065701).

77.80.Bh - Phase transitions and Curie point.
77.80.-e - Ferroelectricity and antiferroelectricity.
64.60.Fr - Equilibrium properties near critical points, critical exponents.

© EDP Sciences 2005