Regensburg 2019 – wissenschaftliches Programm
KFM 14.34: Poster
Mittwoch, 3. April 2019, 16:00–18:30, Poster C
Small bound polarons in LiTaO3 — •Simone Sanna — Institut für Theoretische Physik, Justus-Liebig-Universität Gießen
The optical response of many oxide crystals including the electro-optic material LiNbO3 has been successfully explained by the presence of small polarons. The latter are quasiparticles formed when the interaction of a charge carrier with the surrounding lattice is strong enough to trap the charge carrier at essentially one lattice site. While different kind of small polarons have been described  and demonstrated  in LiNbO3, much less is known concerning the isomorphic and isoelectronic LiTaO3. Although the existence of small bound polarons might be expected due to the high lattice polarizability, the verification of this assumption is still missing. In this work we provide the atomistic description of small bound polarons TaLi5+/4+ in LiTaO3. The calculations performed within density functional theory with Hubbard corrections predict the large lattice relaxation of the oxygen ligands associated to the electronic capture at the antisite center, which can be interpreted as due to the polaron formation. The charge distribution is localized within essentially one unit cell and resembles the atomic Fe dz2 orbitals, suggesting a scarce hybridization the Ta d orbitals.
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