Cooperative response of Pb(ZrTi)O3 nanoparticles to curled electric fields.

We investigate cooperative responses, as well as a microscopic mechanism for vortex switching, in Pb(Zr0.5Ti0.5)O3 nanoparticles under curled electric fields. We find that the domain coexistence mechanism is not valid for toroid switching. Instead dipoles display unusual collective behavior by forming a new vortex with a perpendicular (not opposite) toroid moment. The correlation between the new and original vortices is revealed to be critical for reversing the toroid moment. We further describe a technological approach that is able to drastically reduce the curled electric field needed for vortex switching.