Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.29: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

(contribution withdrawn, see MA 46.2) Pulsed laser deposition and electrical charging of hard magnetic FePt films — •Norman Lange, Karin Leistner, Steffen Oswald, Jens Hänisch, Sebastian Fähler, and Ludwig Schultz — IFW Dresden, PF 27 01 16, 01171 Dresden

Electrical charging of ultrathin ferromagnetic films leading to reversible changes of magnetic properties is attractive for basic research and future nanosized applications. Here we examine the preparation of continuous ultrathin FePt(001) films on Pt/Cr/MgO which can be used as an electrode. An optimum deposition temperature of 450^∘C is found for L10 ordering and perpendicular anisotropy. Lower temperatures lead to a low degree of order, whereas at higher temperatures interdiffusion with the Pt buffer takes place. Films are used as an electrode in an electrochemical cell containing a non-aqueous electrolyte. In-situ Hall measurements are used to characterize the magnetic behaviour in contact with the electrolyte. A reduction of anisotropy is found already without external voltage; an effect connected to the etching of surface iron oxide and the formation of metallic Fe. In the potential range of 2 to 3 V vs. Li/Li+, continuous charging is observed in the current-voltage curves. In this potential range, a continuous reversible increase of moment and corresponding decrease of anisotropy is obtained. Above 3 V vs. Li/Li+, Fe dissolution takes place that results in an irreversible decrease of moment in the in-situ Hall curves.