Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Organic films and electronics, photoorganics; Nanostructures; Plasmonics and nanooptics, Surface chemical reactions and heterogeneous catalysis, Surface dynamics )
O 36.80: Poster
Tuesday, March 12, 2013, 18:15–21:45, Poster B2
Conductance and Relaxations of Magnetic Single-Atom Contacts — Nicolas Néel1, Silke Schröder2, Cesar Lazo2, Paolo Ferriani2, Nico Ruppelt1, •Jörg Kröger3, Stefan Heinze2, and Richard Berndt1 — 1Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany — 2Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany — 3Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
Single-atom contacts fabricated from a Cr-covered tip of a scanning tunnelling microscope and Co and Cr atoms adsorbed to Fe double-layer islands on W(110) exhibit spin-dependent conductances. Depending on the alignment of the magnetic moments of the tip apex and the adsorbed atom the conductance varies by ≈ 40 %. Consequently, these contacts represent atom-sized spin valves. Scrutinizing the spin polarization of the current through these contacts in the vicinity of the tunneling-to-contact transition reveals different geometric relaxations depending on the magnetic moment alignment. Concomitant density functional calculations trace these observations to differently strong exchange forces. The tunnelling anisotropic magnetoresistance is explored at the ultimate limit, i. e., at the single-atom scale. Single Co atoms adsorbed to domains and domain walls of a ferromagnetic Fe film on W(110) exhibit an anisotropy of the magnetoresistance of up to 12 % and repeated sign changes as a function of the bias voltage. Financial support by the Deutsche Forschungsgemeinschaft through SFB 668 is acknowledged.