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O: Fachverband Oberflächenphysik

O 120: Tribology: Surfaces and nanostructures

O 120.5: Vortrag

Freitag, 16. März 2018, 12:30–12:45, MA 144

Pendulum AFM dissipation peaks and surface oxygen vacancies on SrTiO3 — Marcin Kisiel¹, Oleg Brovko², Dilek Yildiz¹, Remy Pawlak¹, Urs Gysin¹, Erio Tosatti², and •Ernst Meyer¹ — ¹Department of Physics, University of Basel,Klingelbergstr. 82, 4056 Basel, Switzerland — ²International Centre for Theoretical Physics (ICTP), P.O.Box 586, I-34151 Trieste, Italy

Bodies in relative motion separated by few nanometer gap experiences a tiny friction force, whose nature is not understood. This non-contact form of friction can be successfully measured by highly sensitive cantilever oscillating like a tiny pendulum over the surface [1].

Recently it was reported that the critical fluctuations at the phase transition in a bulk SrTiO3 may affect the dissipation of mechanical probes even if completely external to the crystal surface [2]. Here we report on striking singlets or multiplets of dissipation peaks above SrTiO3 surface present at low temperatures (T=5K) and after sample annealing to high temperatures (T> 1000oC) which leads to oxygen deficient sample. The observed dissipation peaks are explained as arise due to a tip induced change of valency of the single quantum dot formed by oxygen vacancy (singlet), or groups of vacancies (multiplet). Moreover the results show strong dependence of dissipation peaks on the external magnetic field.

[1] - M. Kisiel et.al., Nature Materials10 (2011), 119-122. [2] - M. Kisiel,et.al., Phys. Rev. Lett.115 (2015), 046101.