Small-polaron conductivity in perovskite ferroelectric BaTiO₃ films
Tyunina, M.; Savinov, M.; Dejneka, A. (2022-11-17)
M. Tyunina, M. Savinov, A. Dejneka; Small-polaron conductivity in perovskite ferroelectric BaTiO3 films. Appl. Phys. Lett. 14 November 2022; 121 (20): 202901. https://doi.org/10.1063/5.0129831
© 2022 Author(s). Published under an exclusive license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in M. Tyunina, M. Savinov, A. Dejneka; Small-polaron conductivity in perovskite ferroelectric BaTiO3 films. Appl. Phys. Lett. 14 November 2022; 121 (20): 202901 and may be found at https://pubs.aip.org/aip/apl/article/121/20/202901/2834641/Small-polaron-conductivity-in-perovskite.
https://rightsstatements.org/vocab/InC/1.0/
https://urn.fi/URN:NBN:fi-fe2023050340473
Tiivistelmä
Abstract
In ABO₃ perovskite oxide ferroelectrics, electrical conductivity ranges from insulator- to superconductor-type and is virtually critical for all applications of these materials. Compared to bulk ceramics and crystals, ferroelectric thin films can enable advanced control of the conductivity. Here, small-polaron hopping conductivity was evidenced and examined in various pulsed-laser-deposited films of ferroelectric BaTiO₃ and reference films of SrTiO₃. For this, AC conductivity was studied in a broad range of temperatures and frequencies for films sandwiched between the bottom and top electrodes. In the BaTiO₃ films, with increasing temperature, a significant increase in activation energy for small-polaron hopping was found and ascribed to strong electron–phonon coupling and complex lattice oscillations therein. Plain relations of the activation energy to microstructure, composition, or phase transitions were lacking, which corroborated the critical role of phonons. Additionally, a phonon-less transport was detected. It was anticipated that owing to strong electron–phonon coupling, rich phonon ensembles, and coexistence of phonon-stimulated and phonon-less processes, the small-polaron conductivity can heavily vary in ferroelectric films that necessitates further studies.
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