Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 2: Surface Magnetism and Spin Phenomena
O 2.8: Talk
Monday, March 16, 2015, 12:30–12:45, MA 004
ISTS of Fe adatoms in contact to superconducting Ta — •Anand Kamlapure1, Lasse Cornils1, Lihui Zhou1,2, Alexander A. Khajetoorians1,3, Jens Wiebe1, and Roland Wiesendanger1 — 1Department of Physics, Hamburg University, Hamburg, Germany — 2Max-Planck Institute for Solid State-Research, Stuttgart, Germany — 3Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
Recent local scale investigations of the competition of superconductivity and magnetism in molecular systems revealed rich physics associated with a quantum phase transition [1]. Here, we experimentally study individual Fe atoms adsorbed on a reconstructed surface of superconducting Ta by inelastic scanning tunneling spectroscopy (ISTS) at a temperature of 1 K and as a function of magnetic field of strength up to 3 T perpendicular to the surface. We observe strong inelastic excitations at three different adsorption sites of the Fe adatoms. The majority site shows a sharp step around 2 meV which is almost independent of the magnetic field. The other two sites exhibit excitations around 1 meV and 4 meV which have a weak magnetic field dependence indicating the magnetic origin of this excitation. In all three cases the superconducting energy gap and coherence peaks are preserved at zero magnetic field indicating very weak coupling between the magnetic moment and the cooper pairs. [1] K. J. Franke et al., Science 332, 940 (2011).