Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 41: Focus Session: Functional Molecules at Surfaces II
O 41.7: Talk
Tuesday, March 17, 2020, 12:30–12:45, TRE Ma
Controlled switching of a single CuPc molecule on Cu(111) — •Thilo Glatzel1, Sweetlana Fremy-Koch1, Ali Sadeghi2, Rémy Pawlak1, Shigeki Kawai3, Alexis Baratoff1, Stefan Goedecker1, and Ernst Meyer1 — 1Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland — 2Department of Physics, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Iran — 3International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
Low temperature measurements of the tunneling current as a function of the applied bias voltage have been performed above individual copper phthalocyanine molecules adsorbed on Cu(111). By tuning of the applied bias, the molecule can be reversibly switched between two configurations. The underlying conformations are revealed by density functional calculations including van der Waals interactions, a C2v symmetric ground state and two energetically equivalent states, in which the molecule is twisted and rotated around its center by +/-7°. For tip biases above 200mV position-dependent current switching is observed, as in previous measurements of telegraph noise [Schaffert et al., Nat. Mater. 12, 223 (2013)]. In a small voltage interval around zero the measured current becomes bistable. Switching to a particular state can be initiated by sweeping the voltage past well-defined positive and negative thresholds at certain positions above the molecule or by scanning at constant current and a reduced reverse bias.