Lecture
WEB Investigation of a correlated nucleation and polarization kinetics in BaTiO3 by means ab initio based molecular dynamics simulations
Wednesday (01.01.2020) 00:30 - 00:45 Part of:The thorough understanding of polarization switching is important both from a scientific and application point of view. The process of polarization switching can be subdivided into nucleation and further nucleus growth. In a defect-free material, a domain wall (DW) may serve as a nucleation centre [1]. In this contribution, we discuss the polarization reversal in BaTiO3 in presence of 180° domain walls. A detailed analysis of nuclei formation and further growth in- and out-of-DW plane are presented. It is known that polarization reversal has to be correlated in space to overcome the electrostatic/electromechanical barriers and form a viable nucleus [2]. In our work, both temporal and spatial correlations of polarization components are studied and are related to an average electrostatic energy of a system. We find that a number of layers and cells is involved in the coherent switching at each particular polarization state.
To approach conditions of a real experiment, we increase an electric field within a finite amount of time. For our simulations, we used the feram code [3] to perform molecular dynamics simulations based on an effective Hamiltonian first introduced by Rabe and Vanderbid [5] allowing for efficient simulation of DW [4].
[1] Young-Han Shin et al., Nature 449, 881–884 (2007)
[2] Jie E. Zhou, at al., Journal of App. Physics 111, 02 (2012)
[3] loto.sourceforge.net/feram/
[4] A. Grünebohm et al., Appl. Phys. Lett. 107, 10 (2015)
[5] W. Zhong et al., Phys. Rev. B 52 (1995)
