Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 66: Oxide Surfaces 2

O 66.1: Topical Talk

Donnerstag, 8. September 2022, 10:30–11:00, S053

Charge-ordered states on incipient ferroelectric polar surfaces — •Cesare Franchini — University of Vienna — University of Bologna

The precise atomic-scale knowledge of surface properties is mandatory for interpreting experimental data, optimizing (photo)catalytic processes, or predicting novel electronic phases. This is particularly challenging for perovskite materials, which typically show a variety of surface structural reconstructions that prevent a generally valid and transferable understanding of surface properties. However, recent experiments have shown that a novel cleavage protocol based on controlled exploitation of ferroelectric instabilities can generate well-defined bulk-terminated (001) surfaces, paving the way for a precise characterization of the surface electronic structure. This talk shall report first principles electronic structure calculations on polar KTaO3(001), focusing on the dichotomy between charge localized/delocalized phases and their impact on surface reactivity. Our data, supported by experimental observations, show that polarity-induced uncompensated carriers in KTaO3(001) exhibit charged-order patterns rather than common 2DEGs, manifested by charge-density wave and (bi)polaron states. Eventually, the trapped charge suppresses ferroelectric surface distortions, resulting in a binary CO adsorption process.

[1] M. Setvin et al. Science 359, 572 (2018). [2] M. Reticcioli et al., Nat. Comm. (2022). [3] Z. Wang et al., Sc. Adv. (2022).