Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Poster Wednesday: Surface Structure, Epitaxy and Growth

O 65.12: Poster

Mittwoch, 3. April 2019, 17:45–20:00, Poster B1

SPA-LEED studies on the Sn/Ge(111) (3× 3) ↔ (√3×√3) Mott-insulator to metal phase transition — •Fabian Thiemann, Semih Özdemir, Christian Brand, Bernd Hafke, Tobias Witte, and Michael Horn-von Hoegen — Universität Duisburg-Essen

An ordered adsorbate layer of 1/3 monolayer of Sn on a Ge(111) surface exhibits a reversible Mott-insulator to metal transition at 173 K [1, 2] which is accompanied by a structural transition from a (3× 3) to (√3×√3) superstructure. Employing spot-profile-analysis low-energy-electron-diffraction allowed the acquisition of high-resolution line profiles and thus an accurate determination of the temperature dependent intensity of the characteristic superstructure spots. Through temperature cycling of the sample starting from the (3×3) ground state at 110 K to the metallic (√3×√3) phase at temperatures above the transition temperature of 173 K we followed the reversible phase transition through k_∥-dependent line profiles taken for each temperature step. The contribution to the spot intensity through the Debye-Waller factor and the structure factor were individually determined.
[1] J. Avila et. al., Phys. Rev. Lett. 82, 442 (1999).
[2] A. V. Melechko et. al., Phys. Rev. B 61, 2235 (2000).