Phase transformation in finite-size ferroelectrics is of fundamental relevance for understanding collective behaviors and balance of competing interactions in low-dimensional systems. We report a first-principles effective Hamiltonian study of vortex-to-polarization transformation in Pb(Zr$_{ 0.5}$Ti$_{ 0.5}$)O$_3$ nanoparticles, caused by homogeneous electric fields normal to the vortex plane. The transformation is shown to (1) follow an unusual { \it macroscopic} path that is symmetry non-conforming and characterized by the occurrence of a previously unknown structure as the bridging phase; (2) lead to the discovery of a striking collective phenomenon, revealing how ferroelectric vortex is annihilated { \it microscopically}. Interactions underlying these behaviors are discussed.
Categories: cond-mat.mtrl-sci