Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 34: Spin Dynamics and Transport: Magnonics
MA 34.1: Vortrag
Mittwoch, 22. März 2017, 09:30–09:45, HSZ 04
Direct Microscopic Observation of Spin Wave Focussing in a Fresnel Lens — •Joachim Gräfe1, Martin Decker2, Kahraman Keskinbora1, Matthias Noske1, Przemysław Gawronski3, Hermann Stoll1, Christian H. Back2, Gisela Schütz1, and Eberhard J. Goering1 — 1MPI für Intelligente Systeme, Stuttgart — 2Universität Regensburg, Regensburg — 3AGH University of Science and Technology, Krakau, Polen
Manipulation of spin waves has recently gained significant scientific interest. Structuring of a spin system on the length scale of the exchange and dipole interactions allows the engineering of spin wave properties. By scanning x-ray microscopy it is possible to image spin wave propagation with spatial and time resolution of about 25 nm and 45 ps with high magnetic contrast based on the XMCD effect. Using this technique we explore the focusing properties of an interference based Fresnel lens for spin waves. We observed a focal spot confined to less than 800 nm at a distance of more than 5 µ m from the zone plate. The intensity is increased by more than 20% above the emission intensity. Thus, the lens is effectively overcompensating the damping during spin wave propagation. Furthermore, the focal spot can be moved easily by changing the applied magnetic bias field in the mT range. Thus, this type of spin wave lens can provide a flexible intense spin wave spot and an effective magnon source for different magnonic or spintronic devices.