SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Poster Session IV: Poster to Mini-Symposium: Infrared nano-optics II
O 52.5: Poster
Dienstag, 2. März 2021, 13:30–15:30, P
Extracting the electronic properties of an oxide two-dimensional electron gas by scanning near-field optical microscopy — •Julian Barnett1, Marc-André Rose2, Georg Ulrich3, Martin Lewin1, Bernd Kästner3, Regina Dittmann2, Felix Gunkel2, and Thomas Taubner1 — 11. Physikalisches Institut (IA), RWTH Aachen — 2Peter Grünberg Institut, Forschungszentrum Jülich — 3Physikalisch-Technische Bundesanstalt Berlin
The interface between bulk insulators SrTiO3 and LaAlO3 (LAO/STO) gives rise to a confined and highly conductive two-dimensional electron gas (2DEG) [1], which poses unique analytical challenges, due to its buried and sensitive nature. Scanning near-field optical microscopy (SNOM) was shown to overcome these challenges by measuring the presence of the LAO/STO 2DEG using highly confined optical near-fields [2], opening the possibility for quantitative analysis by comparison to theoretical predictions. We now introduce spectroscopic s-SNOM measurements of the LAO/STO interface [3], showing that we are able to simultaneously disentangle the 2DEG’s optical response and discriminate between thin film and substrate contributions. This is possible by using full spectroscopy, phonon-enhancement, and more accurate modeling based on the Finite Dipole Model, allowing us to set the starting point for a wave of similar spectroscopic investigations on other nanoscale layered interfaces.
[1] A. Ohtomo et al., Nature 427, 423 (2004).
[2] W. Luo et al., Nat. Commun. 10, 2774 (2019).
[3] J. Barnett et al., Adv. Funct. Mater. 30(46), 2004767 (2020).