The 248th Special CMSM seminar   


Exchange-coupled thin film model systems

Prof. Lambert Alff
Advanced Thin Film Technology,
Institute of Materials Science,
Technische Universität Darmstadt


Date & Time: 11:00 - 12:00, October 4th (Fri), 2019.
Place: 2nd Conference Room, 1st floor, Sengen.

Abstract:

  Exchange-coupled nanocomposites of hard and soft magnetic phases are promising materials for novel green and energy efficient magnets. Not only for permanent magnets, exchange-spring coupled thin films are explored to investigate domain-wall structures in spintronic devices. We present results on the effect of interface roughness on exchange coupling in bilayers of rare-earth free Mn-based hard magnets and FeCo. Furthermore, the combination of 1:5 and 2:17 intermetallics is explored which have the advantage of perfectly matched crystal structures and coherent interfaces. At the example of the system YCo5 -Y2Co17, we show for the first time that a natural phase decomposition during thin film growth can be achieved leading to enhanced energy products. Transmission electron microscopy reveals the nanoscale coexistence of the two phases. In artificial thin film heterostructures of YCo5 - Y2Co17, a perpendicular magnetization can be induced in Y2Co17 by exchange coupling through the epitaxially grown atomically smooth interface.