Polaron-driven surface reconstructions

M. Reticcioli, M. Setvin, X. Hao, P. Flauger, G. Kresse, M. Schmid, U. Diebold, C. Franchini

University of Vienna, Faculty of Physics and Center for Computational Materials Science, 1090 Wien, Austria
Institut für Angewandte Physik, Technische Universität Wien, 1040 Wien, Austria

Phys. Rev. X 7 (2017) 031053

Geometric and electronic surface reconstructions determine the physical and chemical properties of surfaces and, consequently, their functionality in applications. The reconstruction of a surface minimizes its surface free energy in otherwise thermodynamically unstable situations, typically caused by dangling bonds, lattice stress, or a divergent surface potential, and is achieved by a cooperative modification of the atomic and electronic structure. Here, we combined first-principles calculations and surface techniques (scanning tunneling microscopy, non-contact atomic force microscopy, scanning tunneling spectroscopy) to report that the repulsion between negatively charged polaronic quasiparticles, formed by the interaction between excess electrons and the lattice phonon field, plays a key role in surface reconstructions. As a paradigmatic example we explain the (1 × 1) to (1 × 2) transition in rutile TiO2(110).

Corresponding author: Cesare Franchini.

This work has been featured by Giulia Pacchioni in the Research Highlights of Nature Reviews Materials, Nat. Rev. Mater. 2 (2017).

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