Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 23: Magnetization / Demagnetization Dynamics II

MA 23.12: Talk

Wednesday, March 28, 2012, 12:45–13:00, H 1012

Spin-Wave Interference Patterns: Perfect Imaging with Spin-Waves — •Sebastian Mansfeld, Jesco Topp, Kim Martens, Jan-Niklas Toedt, Daniel Mellem, Wolfgang Hansen, Detlef Heitmann, and Stefan Mendach — Institute of Applied Physics, University of Hamburg, Hamburg, Deutschland

We discuss time resolved scanning Kerr microscopy data showing the diffraction of planar Damon-Eshbach spin waves on a one-dimensional grating, realized by a micrometer sized slit array in a Permalloy film. We observe a unique diffraction pattern behind the grating which produces images of the spin-wave field at the slits [1]. In accordance to superlensing concepts known from optical metamaterials [2, 3], these images are formed due to the anisotropic shape of the isofrequency line in k-space defined by the dispersion law for spin waves. A consequence is that the resolution of the observed image is not limited by the wavelength of the spin wave, as is the case in isotropic media. Instead, the image resolution is limited by the curvature of the isoline in k-space and by the damping of the spin wave. We show that the images can be tuned by manipulating the isoline in k-space via the excitation frequency and the external magnetic field.

We gratefully acknowledge support by the DFG via SFB 668, SFB 508, GrK 1286, and by the City of Hamburg via the Cluster of Excellence Nano-Spintronics.

[1] Mansfeld et al., Physical Review Letters, in press (2011) - arXiv:1108.5883v1; [2] Liu et al., Science 315, 1686 (2007); [3] Schwaiger et al., Physical Review Letters 102, 163903 (2009)