Effect of ac field on the dielectric behavior in epitaxial films of relaxor ferroelectricPbMg1∕3Nb2∕3

Abstract

The dynamic dielectric response of epitaxial PbMg 1/3 Nb 2/3 O 3 thin films was experimentally studied as a function of amplitude of ac electric field including very large amplitudes ͑to 10 MV/ m͒. For all amplitudes, a typical glasslike relaxor behavior was evidenced by the Vogel-Fulcher relationship, empirical scaling of the dielectric peak, and a broadening of the relaxation time spectra on cooling. With increasing amplitude of the ac field, both the temperature of the dielectric maxima and the freezing temperature decreased, the relaxation time spectrum became narrower, and the nonlinear permittivity was nonmonotonic. The comparison of the observed dielectric behavior with that under an applied small dc electric field and with the results of modeling revealed an orientational contribution to polarization.

Polarization relaxation in thin-film relaxors compared to that in ferroelectrics

“…6 For RFE as an ensemble of the randomly interacting dipoles with a broad distribution of the local electric field, an analytical description of the dynamic properties is difficult, and it requires numerical simulations. 14,15 In particular, effects of an ac electric field have been simulated using the Monte-Carlo method.…”

“…Vogel-Fulcher relationship, deviation from the Curie-Weiss behavior, temperature evolution of the relaxation time spectra, temperature dependence of the glasslike order parameter, and empirical scaling of the dielectric peak have been found to be similar to those in bulk RFE. 5,6 However, also both the ac field dependent piezoelectric effect and the relatively broad polarization -electric field, or E P − , hysteresis loops have been observed. [7][8][9] A FE-like self-polarized state has been suggested to be responsible for that.…”

“…[7][8][9] A FE-like self-polarized state has been suggested to be responsible for that. 7 On the other side, both the onset of the polar state under an applied dc field 10 and the effects of applied ac field 6 have been demonstrated to result from the orientation of the randomly interacting dipoles in a random field. The presence of FE domains has not been detected.…”

Substrate Clamping Effects on Irreversible Domain Wall Dynamics in Lead Zirconate Titanate Thin Films

“…Strain in epitaxial oxide films has become a universally recognized method for tuning materials properties [1][2][3], enabling novel couplings between magnetic, lattice, and strain behaviors [4][5][6], stabilizing new phases [7] or domain morphologies [8]. Systematic studies of a material's response to strain enable exploration of the fundamental mechanisms responsible for, e.g., the ferroelectric instability [9][10][11][12].While strain effects on intrinsic properties [9,12] and domain morphologies [13,14] are readily amenable to theoretical and experimental studies, their role on local and emergent properties [15] in disordered materials, including polycrystalline ferroelectric films and relaxors, remains virtually unexplored [16,17], Indeed, many of these materials exhibit unique physical properties including giant electromechanical coupling coefficients, broad dispersions of dielectric permittivity, etc. [18][19][20][21].…”

“…While strain effects on intrinsic properties [9,12] and domain morphologies [13,14] are readily amenable to theoretical and experimental studies, their role on local and emergent properties [15] in disordered materials, including polycrystalline ferroelectric films and relaxors, remains virtually unexplored [16,17], Indeed, many of these materials exhibit unique physical properties including giant electromechanical coupling coefficients, broad dispersions of dielectric permittivity, etc. [18][19][20][21].…”