Direct observation of spin-wave focusing by a Fresnel lens
Joachim Gräfe, Paweł Gruszecki, Mateusz Zelent, Martin Decker, Kahraman Keskinbora, Matthias Noske, P. Gawroński, Hermann Stoll, Markus Weigand, Maciej Krawczyk, C. H. Back, E. Goering, Gisela Schütz
Abstract
Spin waves are discussed as promising information carrier for beyond complementary metal-oxide semiconductor data processing. One major challenge is guiding and steering of spin waves in a uniform film. Here, we explore the use of diffractive optics for these tasks by nanoscale real-space imaging using x-ray microscopy and careful analysis with micromagnetic simulations. We discuss the properties of the focused caustic beams that are generated by a Fresnel-type zone plate and demonstrate control and steering of the focal spot. Thus, we present a steerable and intense nanometer-sized spin-wave source. Potentially, this could be used to selectively illuminate magnonic devices like nano-oscillators.