Observation of Polarization Vortices in Complex Oxide Superlattices
Polarization Vortices observed in (PbTiO3)10/(SrTiO3)10 Superlattice via High-Resolution STEM (The figure is an overlay of local polarization vectors, indicated by yellow arrows, on an atomic-resolution STEM image).
Identified the existence of non-uniform polarization vortex states in a ferroelectric material.
Significance and Impact
Topology of such non-uniform polarization fields, will act as a precursor to the search of topological states (such as skyrmions and merons) in ferroelectrics.
- Superlattices of PbTiO3/SrTiO3 were synthesized via Laser-MBE on single crystalline (110) DyScO3 substrates
- Existence of non-uniform Polarization states, including vortex-antivortex pairs, is a strong function of the superlattice periodicity
- Experimental observation of such novel polarization states agrees well with theoretical predictions
- X-ray magnetic circular dichroism shows the “emergence” of a chiral state in such superlattices, although neither STO or PTO are individually chiral