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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.8: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

Preparation of bulk Chromium tips for SP-STM — •André Engel, Anika Schlenhoff, Andreas Sonntag, Stefan Krause, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg

Chromium has proven to be a very useful bulk tip material for spin-polarized scanning-tunneling-microscopy (SP-STM) [1,2]. Recent studies show that bulk Chromium tips allow for atomic resolution and are sensitive to both in-plane and out-of-plane sample magnetization. Compared to ferromagnetic Iron or Nickel, antiferromagnetic Chromium is expected to have a negligible magnetic stray field which otherwise may affect the sample magnetization. In contrast to coated tips, bulk tips do not require any in-situ evaporation or tip exchange mechanism.

Starting with the method and etching parameters proposed in [1,3] we enhanced the preparation of Chromium tips in order to get optimum results regarding tip sharpness and aspect ratio. We present scanning electron microscopy (SEM) images and chemical analysis by means of electron dispersive x-ray spectroscopy (EDX) of differently prepared tips. Influences of different etching solutions, applied voltages and the weight of the insulating polymer tube [3] which physically restricts the etching region to a small area will be discussed.

[1] Li Bassi et al., Appl. Phys. Lett. 91, 173120 (2007)

[2] Schlenhoff et al., Appl. Phys. Lett. 97, 083104 (2010)

[3] Ceballos et al., Surface Science 523, 131 (2003)