Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 51: Poster: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 51.4: Poster

Tuesday, March 13, 2018, 18:15–20:30, Poster B

Potassium Doping of a Correlated Triangular Adatom Lattice — •Julian Maklar, Florian Adler, Jörg Schäfer, and Ralph Claessen — Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, D-97074 Würzburg, Germany

Triangular lattices of localized electrons exhibit a rich phase diagram including spin liquids and exotic superconductivity due to geometric frustration and electronic correlations. Yet, the conditions for these regimes are not fully explored, as experimental realizations are rather limited. The focus of our research is on submonolayer triangular lattices of group IV adatoms on semiconductor substrates. Due to their simplicity and tunability by variation of adatoms and substrates, this material class can serve as a model system to study electronic correlations and frustration.

In this study utilizing ARPES and STM we investigate electron doping by K deposition on a triangular Sn atom lattice on Si(111). At low temperatures, Sn/Si represents a Mott-insulator with row-wise antiferromagnetic order, evident from backfolding of the Sn surface band. Upon K deposition, surprisingly a metal-insulator transition does not emerge. Instead we detect a sharpening of the Sn band followed by a rigid band shift towards higher binding energies. Furthermore, signatures of antiferromagnetic order are destroyed. STM measurements reveal a honeycomb reconstruction of K atoms on the Sn lattice after a deposition of 1/6 monolayer. This setup opens the door to search for exotic states of matter, specifically topological superconductivity.