Evolution of Polarization Vortex Pairs in a Uniaxially Compressed Single-Crystal BaTiO Thin Film: From Initiation to Annihilation.

Using the molecular dynamics method based on the shell model, a uniaxially compressed single-crystal BaTiO thin film with initial polarization configuration of double 90° domains has been simulated. Initiation and vertical propagation of domain switching induced by displacement loading lead to the occurrence of vortices and antivortices in pairs. However, further transverse extension results in separation between vortices and their corresponding antivortices of the same pair and the approach between vortices and antivortices of different pairs. As a result, a complete evolution process of the vortices and antivortices from initiation, to motion, then to collision, and finally to annihilation is observed. The internal mechanism of vortex- antivortex pair evolution is revealed. [ABSTRACT FROM AUTHOR]