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Thickness-Dependent Perovskite Octahedral Distortions at Heterointerfaces
Jennifer Fowlie1, Céline Lichtensteiger1, Marta Gibert1
1Department of Quantum Matter Physics , University of Geneva , 24 Quai Ernest-Ansermet , 1211 Geneva , Switzerland.
Nano Letters
|May 24, 2019
Summary
The study reveals that thin film structure depends on substrate. Continuous interfaces promote stable octahedral patterns, while discontinuous ones cause variations with film thickness.
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- Epitaxial thin films exhibit unique properties influenced by substrate interactions.
- Octahedral tilts and rotations are critical for understanding perovskite oxide behavior.
- Heterointerface quality significantly impacts thin film structural evolution.
Purpose of the Study:
- To investigate the influence of film thickness on octahedral tilts and rotations in LaNiO3 and LaAlO3 thin films.
- To compare the structural behavior of these films grown on different substrates (SrTiO3 and LaAlO3).
- To elucidate the role of epitaxial strain and heterointerface continuity in dictating film structure.
Main Methods:
- Synchrotron X-ray diffraction was employed to measure half-integer Bragg peaks.
- Analysis focused on determining octahedral tilts and rotations as a function of film thickness.
- Films of LaNiO3 and LaAlO3 were grown on SrTiO3 and LaAlO3 substrates.
Main Results:
- A significant difference in octahedral network variation was observed between films on SrTiO3 and LaAlO3 substrates.
- Discontinuous interfaces (LaNiO3/SrTiO3 and LaAlO3/SrTiO3) led to substantial thickness-dependent structural changes.
- Continuous interfaces (LaNiO3/LaAlO3) facilitated the rapid formation of a stable octahedral pattern, consistent with biaxial strain.
Conclusions:
- Heterointerface continuity is a crucial factor, alongside epitaxial strain, in controlling the structural development of thin films.
- Continuous interfaces enable the establishment of predictable octahedral structures even at low film thicknesses.
- Understanding these interfacial effects is key for designing functional oxide thin films.
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