Emergent chirality in the electric polarization texture of titanate superlattices

Padraic Shafer*, Pablo García-Fernández, Pablo Aguado-Puente, Anoop R. Damodaran, Ajay K. Yadav, Christopher T. Nelson, Shang Lin Hsu, Jacek C. Wojdeł, Jorge Iñiguez, Lane W. Martin, Elke Arenholz, Javier Junquera, Ramamoorthy Ramesh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

148 Citations (Scopus)
201 Downloads (Pure)

Abstract

Chirality is a geometrical property by which an object is not super-imposable onto its mirror image, thereby imparting a handedness. Chirality determines many important properties in nature—from the strength of the weak interactions according to the electroweak theory in particle physics to the binding of enzymes with naturally occurring amino acids or sugars, reactions that are fundamental for life. In condensed matter physics, the prediction of topologically protected magnetic skyrmions and related spin textures in chiral magnets has stimulated significant research. If the magnetic dipoles were replaced by their electrical counterparts, then electrically controllable chiral devices could be designed. Complex oxide BaTiO3/SrTiO3 nanocomposites and PbTiO3/SrTiO3 superlattices are perfect candidates, since “polar vortices,” in which a continuous rotation of ferroelectric polarization spontaneously forms, have been recently discovered. Using resonant soft X-ray diffraction, we report the observation of a strong circular dichroism from the interaction between circularly polarized light and the chiral electric polarization texture that emerges in PbTiO3/SrTiO3 superlattices. This hallmark of chirality is explained by a helical rotation of electric polarization that second-principles simulations predict to reside within complex 3D polarization textures comprising ordered topological line defects. The handedness of the texture can be topologically characterized by the sign of the helicity number of the chiral line defects. This coupling between the optical and novel polar properties could be exploited to encode chiral signatures into photon or electron beams for information processing.

Original languageEnglish
Pages (from-to)915-920
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number5
Early online date16 Jan 2018
DOIs
Publication statusPublished - 30 Jan 2018

Keywords

  • Chirality
  • Electric polarization
  • Resonant soft X-ray diffraction
  • Second-principles calculations
  • Topological textures

ASJC Scopus subject areas

  • General

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