Periodic vortex-antivortex pairs in tensile strained PbTiO3 films

Abstract

Topological lattices such as vortices are of importance in both scientific research and application potential. Here, we observed periodic vortex-antivortex pairs in PbTiO3/SrTiO3 multilayered films deposited on orthorhombic (110)-oriented GdScO3 by pulsed laser deposition. Domain patterns of the PbTiO3 layers containing topological structures were analyzed in detail by using advanced transmission electron microscopy. It was found that by increasing the PbTiO3 thickness, a/c domains with extra c domains will form in the triangle a domains in pure flux-closure structures. Atomically resolved high-angle annular dark field-scanning TEM imaging demonstrates that this specific domain structure results in vortex-antivortex pairs at the junctions of extra c domains and the original flux-closure structure, forming a periodic vortex-antivortex array throughout the PbTiO3 layer. These results suggest a pathway for designing new topological structures in ferroelectric films.