Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 2: Surface Magnetism and Spin Phenomena
O 2.5: Vortrag
Montag, 16. März 2015, 11:45–12:00, MA 004
Ballistic Anisotropic Magnetoresistance of Single-Atom Contacts — •Johannes Schöneberg1, Fabian Otte2, Nicolas Néel3, Alexander Weismann1, Yuriy Mokrousov4, Jörg Kröger3, Richard Berndt1, and Stefan Heinze2 — 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 — 4Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
Junctions involving a non-magnetic and a single ferromagnetic layer may exhibit anisotropic magnetoresistance (AMR), i. e., their resistances depend on the magnetization direction relative to the crystallographic axes via spin-orbit coupling. Large AMR effects were predicted for the ballistic transport range but their experimental verification is challenging. We deposited single Co and Ir atoms on domains and domain walls of ferromagnetic Fe layers on W(110) to control their magnetization directions. At a temperature of 5 K they are contacted with nonmagnetic tips in a scanning tunneling microscope to measure the junction conductances. AMR is observed and changes drastically between tunneling and the ballistic regime. First-principles calculations demonstrate that this change is due to a competition of delocalized and localized d states of different orbital symmetry.