The growth morphology of Co(00▪1), grown onto W(110), was studied by using scanning tunneling microscopy and scanning tunneling spectroscopy at 6K. Depending upon the growth conditions, continuous Co films - or Co islands on top of a wetting layer - formed. Dislocation lines appeared within the continuous films, and increased in density after annealing. The Co islands and films exhibited dI/dV curves having a marked peak at -0.3eV below the Fermi energy. The intensity of this peak varied in different areas of the surface. By using monolayer-high islands with a different shape, deposited onto the same Co layer, the differing intensities were attributed to a different stacking of the Co surface. The change in intensity was reproduced by first-principles electronic structure calculations, which revealed that the peak was caused by a surface resonance of minority-spin character which was more strongly coupled to bulk states in the case of hexagonal close-packed (ABA) stacking than in the case of face-centered cubic (ABC) stacking. An increased scanning tunneling spectroscopic intensity of the surface resonance was also found above dislocation lines which were located at the Co/W interface.

Scanning Tunneling Spectroscopy on Co(0001) - Spectroscopic Signature of Stacking Faults and Dislocation Lines. J.Wiebe, L.Sacharow, A.Wachowiak, G.Bihlmayer, S.Heinze, S.Blügel, M.Morgenstern, R.Wiesendanger: Physical Review B, 2004, 70[3], 035404 (13pp)