Abstract-Terahertz-range polar modes in domain-engineered BiFeO3

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

https://journals.aps.org/prl/accepted/60075Y46P531c86a00088064cb6bd9f7f6a05dd72

The dielectric permittivity and properties of electrically active lattice resonances in nanotwinned BiFeO3 crystals have been studied theoretically using an earlier established interatomic potential. The results suggest that an array of 71^\circ domain walls with about 2-5\,nm spacing enhances the static permittivity of BiFeO3 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.