Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 64: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures IV
O 64.12: Vortrag
Mittwoch, 14. März 2018, 18:00–18:15, MA 004
Reversible 2D phase transition driven by an electric field: visualization and control on the atomic scale — Ben Wortmann1, Dennis van Voerden1, •Paul Graf1, Roberto Robles2, Paula Abufager2, Nicolás Lorente2, Christian Bobisch1, and Rolf Möller1 — 1Faculty of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg, Germany — 2ICN2 Catalan Institute of Nanoscience and Nanotechnology, CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
We report on a reversible structural phase transition of a two dimensional system which can be locally induced by an external electric field. [1] By means of scanning tunneling microscopy (STM) we determined two coexisting structural configurations of a CO monolayer on Cu(111): an α-phase (7× 7 superstructure) and a β-phase (3√3 × 3√3) R30∘. The balance of the two phases can be shifted by the electric field of the STM tip, causing the domain boundaries to move, increasing the area of the favored phase controllable both in location and size. If the field is further enhanced new domains nucleate. The arrangement of the CO molecules on the Cu surface is observed in real time and real space with atomic resolution while the electric field driving the phase transition is easily varied over a broad range.Our new manipulation mode permits us to bridge the gap between spontaneous long-range ordering of phase transitions and man-made CO structures created by molecular manipulation of CO adlayers.
[1] B. Wortmann et al., Nano Letters 16 (1), 528-533 (2016)