Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 66: Oxide Surfaces 2

O 66.3: Vortrag

Donnerstag, 8. September 2022, 11:15–11:30, S053

Reversible switching of the 2D electron gas of SrTiO₃(001) studied by HREELS — •Hannes Herrmann, Florian Schumann, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg, Institute of Physics, 06120 Halle, Germany

The formation of a 2D electron gas (2DEG) gained high interest in surface science as it became accessible under oxygen-poor conditions at the TiO₂-terminated SrTiO₃(001) surface [1]. In this work, we follow the 2DEG formation by studying the SrTiO₃ surface plasmon polaritions (SPP) by high-resolution electron energy loss spectroscopy (HREELS). The coupling of the SPP to the 2DEG leads to an asymmetric SPP line shape with extreme broadening. This strong electron-phonon coupling allows to quantify the 2DEG charge carrier density and is used to follow the reversible formation of the 2DEG by heating in UHV/O₂ atmosphere or by adsorbing molecular oxygen at 100 K.
The dielectric response will be discussed in terms of a two-layer model with a surface 2DEG which is modelled using a Drude-like response with a strongly frequency-dependent electronic mobility.

[1] A. F. Santander-Syro, O. Copie, A. Barthelemy, and M. J. Rozenberg, Nature 469, 189 (2011).