LetterShape-induced phase transition of vortex domain structures in ferroelectric nanodots and their controllability by electrical and mechanical loads

•Dipole configuration in a ferroelectric nanodot depends on the symmetry of its shape.•BaTiO3 ultrathin nanoplatelet exhibits a tetragonal vortex domain structure.•We report a novel vortex domain structure in BaTiO3 nanodots.•Behaviors of the novel vortex are well controlled by electric field and stress.

Shape-induced phase transition of vortex domain structures (VDSs) in BaTiO3 (BT) nanodots under open circuit boundary condition have been investigated using an effective Hamiltonian method. Our calculation indicates the tetragonal VDS missing in cubic BT nanodots can be induced by varying the shape of a nanodot from cube to platelet. Interestingly, a novel VDS is found in BT nanoplatelets in our simulations. Further investigation shows that it is a result of compromise between the ground state and the symmetry of the shape of the nanodot. Furthermore, based on the novel VDS, routes of controlling VDSs governed by homogeneous electric field and uniform stress are discussed. In particular, our results show the possibility of designing multi-states devices based on a single VDS.