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Observation of Polarization Vortices in Complex Oxide Superlattices

Observation of Polarization Vortices in Complex Oxide SuperlatticesPolarization 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).

Scientific Achievement
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.

Research Details

  • 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

A.K. Yadav, C.T. Nelson, S.L. Hsu, Z. Hong, J.D. Clarkson, C.M. Schlepüetz, A.R. Damodaran, P. Shafer, E. Arenholz, L.R. Dedon, D. Chen, A. Vishwanath, A.M. Minor, L.Q. Chen, J.F. Scott, L. W. Martin, R. Ramesh, Nature (2016) doi:10.1038/nature16463