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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 17.7: Vortrag

Mittwoch, 7. September 2022, 17:15–17:30, H3

The polar KTaO₃ (001) surface: Electronic structure and CO adsorption — Zhichang Wang¹, Michele Reticcioli², Zdenek Jakub¹, Michael Schmid¹, Gareth Parkinson¹, Ulrike Diebold¹, Cesare Franchini², and •Martin Setvin³ — ¹TU Wien, Vienna, Austria — ²University of Vienna, Vienna, Austria — ³Charles University, Prague, Czech Republic

Polar surfaces offer intriguing physical and chemical properties applicable in electronics or catalysis. Cleaving the KTaO₃ perovskite along its polar (001) plane provides a well-defined, bulk-terminated surface with KO and TaO₂ terminations [1]. As-cleaved surfaces exhibit a high concentration of in-gap states; these electrons predominantly reside at the TaO₂-terminated parts of the surface. These electrons can affect surface chemistry, as is demonstrated for CO molecules. CO has two adsorption configurations on the TaO₂ termination, and the CO differs in how it couples to the excess electrons. DFT calculations indicate that CO preferentially couples to electron bipolarons.

The work was supported by FWF project P32148-N36, by GACR 20-21727X and GAUK Primus/20/SCI/009.

[1] M. Setvin, M. Reticcioli, F. Poelzleitner et al., Science 359, 572 (2018)