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

November 12, 2014

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 Sr}dn+1}uTi_nuO_3n+1u (n=1-6) phases. They showed that the Curie temperature T_cu 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 SR}dn+1}uTi_nuO_3n+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 T_cu. 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

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Journals

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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_n+1uTi_nuO_3n+1u*, Advanced Functional Materials, [online], https://doi.org/10.1103/PhysRevB.90.174105 (Accessed December 11, 2024)