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Influence of the central mode and soft phonon on the microwave dielectric loss near the strain-induced ferroelectric phase transitions in Srn+1uTinuO3n+1u*

Published

Author(s)

V. Goian, S. Kamba, D Nuzhnyy, Nathan Orloff, T. Birol, C.-H Lee, D. G. Schlom, James Booth

Abstract

Recently, Lee et al.[1]used1% tensile strain to induce a ferroelectic instability in thin films of Srdn+1uTinuO3n+1u (n=1-6) phases. They showed that the Curie temperature Tcu gradually increased with n, reaching 180 K for Sr7Ti6O19 (n=6). The permittivity of the n=6 sample could also be tuned significantly by the application of an electric field with exceptionally low dielectric loss at 300K, rivaling all known tunable microwave dielectrics. [1] Here, we present microwave (MW), infrared and THz spectra of strained SRdn+1uTinuO3n+1u thin films deposited on (110) DyScO3u. Near the ferroelectric phase transitions we observe the splitting and shifting of phonon and central mode frequencies, demonstrating the change of crystal symmetry below Tcu. Moreover, our spectra reveal that hte central mode contribution dominates MW loss. In the Sr7uTi6uO19u thin film the central mode vanishes at 300 K, explaining its low MW loss. Finally we discuss the origin and general conditions for the appearance of central modes near ferroelectric phase transitions.
Citation
Advanced Functional Materials

Keywords

microwave, dielectric loss, tenability, soft modes, cental modes, phonons

Citation

Goian, V. , Kamba, S. , Nuzhnyy, D. , Orloff, N. , Birol, T. , Lee, C. , Schlom, D. and Booth, J. (2014), Influence of the central mode and soft phonon on the microwave dielectric loss near the strain-induced ferroelectric phase transitions in Sr<sub>n+1</sub>uTi<sub>n</sub>uO<sub>3n+1</sub>u*, Advanced Functional Materials, [online], https://doi.org/10.1103/PhysRevB.90.174105 (Accessed April 21, 2024)
Created November 11, 2014, Updated October 12, 2021