Field-induced vortices in weakly anisotropic ferroelectrics

In the micro- and nanoscale ferroelectric samples, the formation and the growth of domains are the usual stages of the polarization switching mechanism. By assuming the weak polarization anisotropy and by solving the Ginzburg-Landau-Khalatnikov equation we have explored an alternative mechanism which consists in ferroelectric switching induced by vortex formation. We have studied the polarization dynamics inside a ferroelectric circular capacitor where switching leads to formation of a metastable vortex state with a rotational motion of polarization. Our results are consistent with recent first-principa simulations [I. I. Naumov and H. X. Fu, Phys. Rev. Lett. 98, 077603 (2007)] and with experiments in PbZr0.2Ti0.8O3 [A.Gruverman et al, J. Phys. Condens. Matter 20 342201(2008)] and demonstrate that vortex induced polarization switching can be the effective mechanism for circular nano-capacitors.