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arXiv · 2205.11604

Switchable Electric Dipole from Polaron Localization in Dielectric Crystals

Kazuki Morita·Yu Kumagai·Fumiyasu Oba·Aron Walsh
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Abstract

Ferroelectricity in crystals is associated with the displacement of ions or rotations of polar units. Here we consider the dipole created by donor doping ($D^+$) and the corresponding bound polaron ($e^-$).A dipole of 6.15 Debye is predicted, from Berry phase analysis, in the Ruddlesden-Popper phase of ${\rm Sr_3Ti_2O_7}$. A characteristic double-well potential is formed, which persists for high doping densities. The effective Hubbard $U$ interaction can vary the defect state from metallic, a two-dimensional polaron, through to a zero-dimensional polaron. The ferroelectric-like behavior reported here is localized and distinct from conventional spontaneous lattice polarization.

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Kazuki Morita, Yu Kumagai, Fumiyasu Oba, Aron Walsh. 2022-05-23. Switchable Electric Dipole from Polaron Localization in Dielectric Crystals. https://doi.org/10.1103/physrevlett.129.017601

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