Abstract-Terahertz-Range Polar Modes in Domain-Engineered BiFeO 3

Jirka Hlinka, Marek Paściak, Sabine Körbel, and Pavel Marton

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.057604

The dielectric permittivity and properties of electrically active lattice resonances in nanotwinned ${\mathrm{BiFeO}}_3$crystals have been studied theoretically using an earlier established interatomic potential. The results suggest that an array of 71° domain walls with about 2–5 nm spacing enhances the static permittivity of ${\mathrm{BiFeO}}_3$ by more than an order of magnitude. This enhancement is associated with an electrically active excitation, corresponding to a collective vibration of pinned domain walls at a remarkably high frequency of about 0.3 THz.

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