Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 17: Focus Session: Surfaces and Interfaces of (Incipient) Ferroelectrics (joint session O/KFM)

KFM 17.8: Vortrag

Mittwoch, 7. September 2022, 17:30–17:45, H3

Polarons and ferroelectricity: tip-induced phenomena on oxide perovskite surfaces — •Dominik Wrana1, Igor Sokolović2, Jesus Redondo1, Pavel Kocán1, Aji Alexander1, Llorenç Albons1, and Martin Setvin11Department of Surface and Plasma Science, Charles University, Prague, Czech Republic — 2Institute of Applied Physics, TU Wien, Vienna, Austria

In this talk, I will present the similarities and differences between two representative perovskite oxide surfaces: KTaO3(001) and BaTiO3(001), showcasing the manifestation of the (incipient-) ferroelectricity on the atomic and electronic structure. Both surfaces were prepared by cleaving single crystals in situ and characterized by means of qPlus nc-AFM at temperatures ranging from 4K to 100K.

Bulk-terminated KTaO3(001) develops two alternating domains of KO and TaO2 [1]. Excess electrons injected from the AFM tip form quasiparticles called polarons (charges coupled with lattice distortions) which can be further shaped into 1D or 2D structures by emerging electric fields.

Different mechanism applies in the case of BaTiO3(001), where at low temperatures titanium atoms can easily break the symmetry causing a spontaneous polarization. Hence, a biased tip allows for reversible manipulation of individual atoms on the surface: writing and erasing polarized ferroelectric domains.

[1] Setvin, Martin, et al. Science 359.6375 (2018): 572-575

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