Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: Methods: Scanning probe techniques I

O 3.7: Vortrag

Montag, 22. März 2010, 12:45–13:00, H32

Characterization of tips for spin-polarized scanning tunneling microscopy — Guillemin Rodary, •Sebastian Wedekind, Hirofumi Oka, Dirk Sander, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle

A common procedure to prepare tips for spin-polarized scanning tunneling microscopy is to deposit magnetic materials onto a W-tip, which was electrochemically etched and subsequently flashed to 2200 K under UHV conditions [1]. However, this macroscopic tip preparation does not necessarily yield a certain magnetic sensitivity. We show that depositing Cr or Co/Cr bilayers on a W-tip can lead to vastly different magnetic tip responses in external fields [2]. We find that the microscopic tip preparation by voltage pulses under imaging conditions is decisive for the resulting magnetic configuration at the tip apex. We propose a conclusive characterization of the magnetic configuration of the tip apex. We show that both careful tip preparation and characterization by tunneling spectroscopy need to be augmented by measurements in magnetic field to ensure a reliable analysis of a magnetic contrast in spin-polarized scanning tunneling microscopy studies. [1] R. Wiesendanger, Rev. Mod. Phys. 81 (2009)1495. [2] G. Rodary, S. Wedekind, H. Oka, D. Sander, J. Kirschner, Appl. Phys. Lett. 95 (2009) 152513.