Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Ferroics – Domains and Domain Walls 1

KFM 14.7: Vortrag

Mittwoch, 7. September 2022, 11:45–12:05, H5

Oxygen vacancies nucleate domain walls in ferroelectrics — •Urko Petralanda1, Mads Kruse1, Hugh Simons2, and Thomas Olsen11CAMD, Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark — 2Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark

Domain walls are topological defects which emerge spontaneously in ferroelectrics [1]. At charged domain walls (CDW), free charge from the bulk is promoted to the conduction band through a band-bending mechanism, to compensate their local bound charge [2]. This creates highly conductive embedded mobile 2D nanosheets, suitable for nanoelectronics related applications [2]. Oxygen vacancies are believed to play a role in helping CDW overcome their strong electrostatic interaction. In this work [3], by means of density functional theory calculations in BaTiO3 we clarify the screening mechanism of CDW charge in both pristine and oxygen vacancy aided cases, and we propose that, beyond the commonly accepted view of oxygen vacancies as CDW stabilizers, they can actually ignite the formation of CDW. We explain the experimentally observed difference in electronic conductivity of the positively and negatively charged CDW in BaTiO3, as well as the generic prevalence of CDW in ferroelectrics. Such a vacancy driven CDW formation implies that specific charged domain wall configurations may be realized by bottom-up design.

[1] G. Catalan et al, Rev. Mod. Phys. 84, 119 (2012)

[2] T. Sluka et al, Nat. Commun. 4, 1808 (2013).

[3] U Petralanda et al, Phys. Rev. Lett. 127, 117601 (2021)

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