Optically Induced Picosecond Lattice Compression in the Dielectric Component of a Strongly Coupled Ferroelectric/Dielectric Superlattice. (28th December 2021)

• Record Type: Journal Article
• Authors: Sri Gyan, Deepankar; Lee, Hyeon Jun; Ahn, Youngjun; Carson, River B.; Carnis, Jerome; Kim, Tae Yeon; Unithrattil, Sanjith; Lee, Jun Young; Chun, Sae Hwan; Kim, Sunam; Eom, Intae; Kim, Minseok; Park, Sang‐Youn; Kim, Kyung Sook; Lee, Ho Nyung; Jo, Ji Young; Evans, Paul G.
• Is Part Of: Advanced Electronic Materials. Volume 8:Number 6(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-28
• Subjects: depolarization‐field screening -- ferroelectric/dielectric superlattice -- ultrafast structural phenomena -- X‐ray free‐electron laser diffraction; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.202101051
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: Above‐bandgap femtosecond optical excitation of a ferroelectric/dielectric BaTiO3 /CaTiO3 superlattice leads to structural responses that are a consequence of the screening of the strong electrostatic coupling between the component layers. Time‐resolved X‐ray free‐electron laser diffraction shows that the structural response to optical excitation includes a net lattice expansion of the superlattice consistent with depolarization‐field screening driven by the photoexcited charge carriers. The depolarization‐field‐screening‐driven expansion is separate from a photoacoustic pulse launched from the bottom electrode on which the superlattice is epitaxially grown. The distribution of diffracted intensity of superlattice X‐ray reflections indicates that the depolarization‐field‐screening‐induced strain includes a photoinduced expansion in the ferroelectric BaTiO3 and a contraction in CaTiO3 . The magnitude of expansion in BaTiO3 layers is larger than the contraction in CaTiO3 . The difference in the magnitude of depolarization‐field‐screening‐driven strain in the BaTiO3 and CaTiO3 components can arise from the contribution of the oxygen octahedral rotation patterns at the BaTiO3 /CaTiO3 interfaces to the polarization of CaTiO3 . The depolarization‐field‐screening‐driven polarization reduction in the CaTiO3 layers points to a new direction for the manipulation of polarization in the component layers of a strongly coupled ferroelectric/dielectric superlattice. Abstract : Optical excitation screens the strong electrostatic coupling between the component layers of a ferroelectric/dielectric BaTiO3 /CaTiO3 superlattice. The structural response to optical excitation includes a net lattice expansion consisting of the sum of expansion in ferroelectric BaTiO3 and contraction in CaTiO3 . The depolarization‐field‐screening‐driven polarization reduction in CaTiO3 points to new directions for the manipulation of nanoscale polarization.