Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 69: Metal Substrates: Clean Surfaces

O 69.4: Vortrag

Freitag, 30. März 2007, 11:00–11:15, H41

Real-space observation of the Kondo-effect on deeply burried Co-Atoms — •Alexander Weismann, Martin Wenderoth, and Rainer Ulbrich — IV. Physikalisches Institut Universität Göttingen; Friedrich Hund Platz 1; 37077 Göttingen

Isolated Co Atoms beneath the Cu(100) surface were prepared by simultaneous deposition of host-metal and impurity-compound under UHV-conditions. Scanning Tunnelling Spectroscopy performed at 6K shows highly anisotropic bulk Friedel-oscillations around the impurities which can be detected even for impurity depths of 15 ML. Due to the real-space properties of the single electron propagator, which depends decisively on details of the host-metals Fermi-surface, the electron density is only influenced in narrowly defined directions from the impurity (electron focusing). A distinct phase-shift of the LDOS-oscillations can be observed around zero bias as a direct consequence of the Kondo resonance of the Co impurity. dI/dU(U) spectra exhibit Fano-lineshapes with a spatially dependent asymmetry. These can be observed only within the regions of high LDOS-modulation while no spectral feature is present directly above a deep Co-Atom.