Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.109: Poster

Tuesday, March 27, 2012, 18:15–21:45, Poster B

Chromium Bulk Tips for Spin-Polarized Scanning Tunneling Microscopy — •Christian Hanneken, André Kubetzka, Kirsten von Bergmann, and Roland Wiesendanger — Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany

For the investigation of magnetic nanostructures using spin-polarized scanning tunneling microscopy (SP-STM), one would like to avoid uncontrolled magnetic interactions between tip and sample and the tip and an external magnetic field. Antiferromagnetic material features these properties, therefore being desirable as a tip material. In this work, a new method is presented for the production of antiferromagnetic chromium bulk tips. The electrochemically etched tips were characterized ex situ using scanning electron microscopy. In order to demonstrate the magnetic sensitivity of the produced tips, one tip was characterized in situ using SP-STM. The polar angle of the tip magnetization and its variation after different tip changes is determined and is found not to change significantly. In addition, it is shown that an external magnetic field has no effect on the tip magnetization up to B = ±2 T. To conclude, this Chromium bulk tip is found to be similar to Cr coated W tips with the advantage of a nearly infinite amount of magnetic material.