Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 14: Metal Substrates: Epitaxy and Growth

O 14.7: Talk

Monday, March 26, 2007, 15:45–16:00, H39

The growth of Co on Cr/W(110) investigated by STM and STS — •Torsten Methfessel and Hans Joachim Elmers — Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, D-55099 Mainz

Highly spinpolarised metals are of great interest e.g. for the application in spin-valves. Recently observed large tunneling magnetoresistance effects indicate that the metastable bcc phase of Co provides a high spin-polarisation at the Fermi edge. Previous investigations of Co on Cr(110) with high-resolution low-energy electron diffraction (LEED) indicated pseudomorphic growth of bcc-Co on Cr(110) [1]. In order to prepare a Cr(110) substrate, we deposited a 8 ML Cr film on W(110) that was annealed to 500 K. The annealing results in high islands with a perfect Cr(110) surface, that serves as a substrate for Co. Using STM and STS we investigated local structural and electronic properties of the Co films. While the Co monolayer is pseudomorphic to the Cr(110) surface we oberserve significant variations of the local conductivity on thicker Co coverages indicating different electronic structures. The variation of the electronic structure results from different crystallographic structures of the Co. Comparing the tunneling spectra with previously measured spectra of pure Co films on W(110) [2] we conclude that the Co grows in a hcp and fcc structure. Areas with different stacking sequences are separated by dislocation lines similar to the growth of Co on W(110).

[1] S. Fölsch et al., Phys.Rev.B 57, R4293 (1998).

[2] M. Pratzer et al Phys.Rev.B 72, 035460 (2005).