Pressure-dependent phase transitions in hybrid improper ferroelectric Ruddlesden-Popper oxides

Clarke, Gabriel; Daisenberger, Dominik; Luo, X.; Cheong, S. W.; Bristowe, Nicholas C.; Senn, Mark S.

Abstract

The temperature-dependent phase transitions in Ruddlesden-Popper oxides with perovskite bilayers have been under increased scrutiny in recent years due to the so-called hybrid improper ferroelectricity that some chemical compositions exhibit. However, little is currently understood about the hydrostatic pressure dependence of these phase transitions. Herein we present the results of a combined high-pressure powder synchrotron x-ray diffraction experiment and abinitio study on the bilayered Ruddlesden-Popper phases Ca3Mn2O7 and Ca3Ti2O7. In both compounds we observe a first-order phase transition, that in combination with our density functional theory calculations, we can confidently assign as being between polar A21am and nonpolar Acaa structures. Interestingly, we show that while the application of pressure ultimately favors a nonpolar phase, as is commonly observed for proper ferroelectrics, regions of response exist where pressure actually acts to increase the polar mode amplitudes. The reason for this can be untangled by considering the varied response of octahedral tilts and rotations to hydrostatic pressure and their trilinear coupling with the polar instability. Published by the American Physical Society 2024

Citation

Clarke, G., Daisenberger, D., Luo, X., Cheong, S. W., Bristowe, N. C., & Senn, M. S. (2024). Pressure-dependent phase transitions in hybrid improper ferroelectric Ruddlesden-Popper oxides. Physical Review B, 109(9), Article 094107. https://doi.org/10.1103/physrevb.109.094107

• Journal Article Type: Article
• Acceptance Date: Feb 29, 2024
• Online Publication Date: Mar 15, 2024
• Publication Date: Mar 1, 2024
• Deposit Date: Mar 19, 2024
• Publicly Available Date: Mar 20, 2024
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 109
• Issue: 9
• Article Number: 094107
• DOI: https://doi.org/10.1103/physrevb.109.094107
• Public URL: https://durham-repository.worktribe.com/output/2332141