Domain wall contribution to the nonlinear dielectric response: effective potential model

Author(s)

Placeres-Jimenez, R. ^[1] ; Rino, J. P. ^[1] ; Goncalves, A. M. ^[2] ; Eiras, J. A. ^[2]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Fis, Grp Simulacao Computac, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos, Dept Fis, Grp Mat Ferro, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF PHYSICS D-APPLIED PHYSICS; v. 48, n. 46 NOV 25 2015.
• Web of Science Citations: 0

Abstract

Domain wall displacement has an important contribution to the different nonlinear dielectric responses observed in ferroelectrics. For a moderated alternating electric field, domain walls perform a small displacement around their equilibrium positions. Such motion of the domain walls can be modelled as a body moving in a viscous medium under the action of an effective potential W(l). From this model the dispersion relationships are derived. The exact expression for the effective potential is found assuming that the dielectric permittivity depends on the electric field strength as epsilon proportional to 1/(alpha + beta E-2). The effect of multidomain structure and polarization hysteresis are introduced through the effective field approximation E-eff equivalent to E + kappa P(E). An important merit of the model is that it allows the simulation of transient polarization processes for the arbitrary input signal, predicting a power law for the polarization and depolarization currents. An analytic expression is found for the dependence of the permittivity on the electric field strength that correctly reproduces its hysteretic behaviour. The polarization loop and nonlinear dielectric response for subswitching the alternating electric field are simulated and compared with experimental data obtained from PZT thin films. It was observed that the simulated dielectric loss was lower than the experimental one, which can be explained as a result of the interaction of domain walls with defects. Point defects are introduced into the model as a perturbation of the effective potential, showing the dependence of the dielectric loss on the concentration of the defects. (AU)

• FAPESP's process: 13/18874-7 - Nanostructure Ferroelectric Perovskites: Domain Wall Collective Motion Modeling and Classical Molecular Dynamics Simulation
• Grantee: Rolando Placeres Jiménez
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 08/04025-0 - Nanostructured multifunctional multiferroic materials: synthesis, properties, phenomenology and applications
• Grantee: José Antonio Eiras
• Support Opportunities: Research Projects - Thematic Grants