Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 24: Oberfl
ächenmagnetismus

MA 24.7: Vortrag

Dienstag, 8. März 2005, 12:00–12:15, TU A060

Spin-polarized scanning tunneling microscopy of ultrathin Fe/Mo(110) films — •J. Prokop, A. Kukunin, and H.J. Elmers — Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, D-55099 Mainz

We report on magnetic contrast observed by low-temperature (5 K) spin-resolved scanning tunnelling microscopy (SP-STM) of Fe nanowires deposited on a Mo(110) single crystal. Magnetic information is obtained from the conductivity map. Magnetic contrast is achieved using tungsten tips covered by Au/Co thin films. The W tips were flashed at ∼ 2000 K, and subsequently covered by 10 ML thick Au and Co layers at RT. Due to the spin reorientation transition of Co films on Au an out-of-plane magnetic sensitivity is obtained for thin cobalt films, while for thicker Co coverages an in-plane magnetization component can be probed. The iron nanowires were prepared by step flow growth onto the Mo(110) substrate kept at 700 K during molecular beam epitaxy (MBE) in ultra high vacuum (UHV). We find that the 1 ML thick ferromagnetic Fe nanowires reveal a magnetization perpendicular to the surface [1]. Double layer (DL) nanowires show a perpendicular easy axis, too. Due to the dipolar coupling adjacent nanowires are mostly antiparallely magnetized. The domain wall width observed in DL stripes is ∼ 3 nm, similar to the width observed in ML stripes [1]. The reorientation of the tip sensitivity axis was confirmed by SP-STM measurements of thicker Fe/Mo(110) films.

[1] M. Bode et al., Phys. Rev. Lett. 92, 067201 (2004).