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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.88: Poster

Freitag, 26. März 2010, 11:00–14:00, Poster B1

A variable-temperature ultra-high vacuum four-probe spin-polarized scanning tunnelling microscope — •Tobias Spitz, Shiro Yamazaki, Oswald Pietzsch, and Roland Wiesendanger — Institute of Applied Physics and Microstructure Advanced Research Center, University of Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany

A variable-temperature UHV four-probe spin-polarized scanning tunnelling microscope (SP-STM) is presented. The instrumental possibilities of a commercial system (Omicron's Nanoprobe) were substantially extended. Facilities for in-situ preparation of spin-polarized tips, as required for SP-STM and spin-resolved tunneling spectroscopy (SP-STS), were designed, built, and tested. An electron beam heating stage was constructed for removing surface oxides at the tip apex by flashing the tip to temperatures up to 2000K follwed by a subsequent magnetic thin film deposition process. It is a major challenge in transport experiments involving surface nanostructures to avoid leak currents through the underlying substrate. The necessary decoupling of the nanostructures and substrate can be achieved by a NaCl buffer layer as has been shown previously. The design of an appropriate home-built evaporator is presented.