The contribution of the ferroelectric soft mode to dielectric permittivity gives rise to the possibility of tuning the properties of material by means of an electric field when the soft mode has low enough frequency, and this has been used in many applications, where a strong static permittivity is required. In this contribution, conditions for observation of tunable terahertz-range dielectric resonances, associated with the presence of nanoscale ferroelectric domains, will be discussed. The starting point will be dielectric characterization of ferroelectric BiFeO3 thin films and ceramic samples[1], and the very recent theoretical prediction of an occurrence of a peculiar terahertz resonance in BiFeO3 [2].
This work was supported by the Czech Science Foundation (Project GACR 13-15110S) and by European Union funding under the 7th Framework Programme (Project NOTEDEV).
References
[1] S. Skiadopoulou, V. Goian, C. Kadlec, F. Kadlec, X. F. Bai, I. C. Infante, B. Dkhil, C. Adamo, D. G. Schlom, and S. Kamba, Phys. Rev. B 91, 174108 (2015).
[2] J. Hlinka, M. Pasciak, S. Korbel and P. Marton, In press (2017).