Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 120: Tribology: Surfaces and nanostructures
O 120.4: Vortrag
Freitag, 16. März 2018, 12:15–12:30, MA 144
Electrostatic Friction on Bi2Te3 (0001) — •Dilek Yildiz1,2, Marcin Kisiel1,2, Urs Gysin1, Oguzhan Gürlü3, and Ernst Meyer1 — 1Universität Basel, Basel, Switzerland — 2Swiss Nanoscience Institute, Basel, Switzerland — 3Istanbul Technical University, Department of Physics, Istanbul, Turkey
Bi2Te3 belonging into the class of topological insulators, has a bandgap in the bulk that makes the crystal semiconductor, whereas its surface is protected from backscattering. While protected topological systems are promising to observe exotic physical phenomena like Majorana fermion bounded state or magnetic monopoles, their frictional responses remain to be studied. Although in general 2D electronic systems are expected to strongly enhance the electrostatic friction, there is still lack of experimental evidence of it. Here we study electronic nature of Bi2Te3 surface and its effect on frictional response of the crystal by means of combined pendulum AFM/STM. While quantized image potential states which are above vacuum level were observed with STM, huge energy dissipation peaks were observed few nanometers above the surface with pendulum AFM. Energy dissipation peaks are localized at relatively large voltages as expected for image states and observed to be shifted to even higher voltages as tip-sample distance increase. Their relation was investigated in more detail by simultaneously operating STM and AFM. In this study, we observed that dissipation peaks are mainly due to electrostatic friction and closely related to image potential states.