Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: Methods: Scanning probe techniques I

O 3.6: Vortrag

Montag, 22. März 2010, 12:30–12:45, H32

Challenges in constructing spin-polarized scanning probe tips — •Thorsten Wutscher and Franz J. Giessibl — Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg

A central feature of scanning force microscopy (SFM) is the force dependence upon the atomic configuration and chemical identity of the tip [1, 2]. Spin-polarized tips, created with an external magnetic field, have been shown to yield spin contrast at the atomic scale [3]. In order to detect spin contrast, the apex atom has to be a magnetic atom, the spins between tip and sample should be (anti-)parallel to each other and the magnetic moment of the apex atom has to be stable. Given an appropriate tip selection, this should be possible at room temperature without the presence of an external magnetic field. In situ cleaved tips can avoid contamination near the tip-sample junction. Nickel oxide was chosen as a candidate tip material because it has a high Néel temperature and a common magnetic bulk and surface alignment. It has a rock salt structure and thus cleaves well. The tips were oriented on a quartz cantilever (qPlus sensor) for SFM experiments.

[1] Y. Sugimoto, P. Pou, M. Abe, P. Jelinek, R. Pérez, S. Morita and Ó. Custance, Nature, 446, 64-67 (2007)

[2] S. Hembacher, F. J. Giessibl, J. Mannhart, Science, 305, 380-383 (2004)

[3] U. Kaiser, A. Schwarz, R. Wiesendanger, Nature, 446, 522-525 (2007)