Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 15: STM/AFM: New Approaches

O 15.5: Vortrag

Montag, 7. März 2016, 16:15–16:30, H24

Influence of tip sharpness on subatomic resolution capability of atomic force microscopy — •Julian Berwanger, Ferdinand Huber, and Franz Josef Giessibl — Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany

By lateral manipulation, we show that the predicted diffusion barrier of 28.5meV of a single iron adatom [1] is lowered due to the presence of the tip by about 70% [2] and that the force responsible for manipulation is purely attractive for both Cu-terminated and CO-terminated tips. Moreover, we find that the metallic background of the functionalized tips strongly influences the tip-adatom interaction and the appearance of adatoms in the AFM channel. In a pyramidical tip model an increase of the apex angle from 126.0° to 126.9° already change the tip-adatom interaction from purely attractive to preferably repulsive. The tip with the apex angle of 126.0° can image adatoms at a by 30pm reduced tip-sample-distance compared to the tip with an apex angle of 126.9°. Subatomic resolution can only be obtained at relatively close tip-sample distances. Therefore we suggest that only "sharp" CO-terminated tips allow subatomic resolution [3]. [1] N. N. Negulyaev et al. PRB 79, 195411 (2009), [2] M. Emmrich et al. PRL 114, 146101 (2015), [3] M. Emmrich et al. Science 348, 308 (2015)