Linear excitation of short propagating spin waves via a pair of layered vortex cores


Linear excitation of short propagating spin waves via a pair of layered vortex cores

Wintz, S.; Weigand, M.; Tyberkevych, V. S.; Slobodianiuk, D. V.; Stoll, H.; Raabe, J.; Neudert, A.; Erbe, A.; Lindner, J.; Slavin, A. N.; Fassbender, J.

The investigation of spin wave dynamics in nanomagnetic systems is one of the key topics in modern magnetism. To excite short spin waves, it is typically necessary either to use transducers of the size of a wavelength (micro-striplines or point-contacts) or to excite the spin waves parametrically by a double-frequency spatially uniform microwave signal. Here we demonstrate that the efficient linear excitation of short propagating spin waves is possible in a trilayer in which the magnetic layers form a vortex pair with opposite circulations and parallel cores. Such spin waves are directly observed by time-resolved x-ray microscopy upon application of microwave magnetic fields of appx. 1 mT. We find that for excitation frequencies in the GHz regime, the resulting spin wavelength is continuously tunable in a range between 50 nm and 500 nm by this frequency. Here, the radial spin wave propagation direction depends on the total handedness of the two vortex circulations, revealing a clear non-reciprocity of the spin waves observed. Both, analytic theory and micromagnetic simulations show that such a nanomagnetic system supports a gapless spin wave branch with linear dispersion and strong nonreciprocity, and that the propagating spin waves belonging to this branch can be excited by a spatially uniform microwave signal. Other excitation mechanisms, such as spin-transfer torques or thermal gradients, could be utilized to generate spin waves in the system presented.

  • Poster
    Gordon Research Conferences: Spin Dynamics in Magnetic Nanostructures, 18.08.2013, Hong Kong, China

Permalink: https://www.hzdr.de/publications/Publ-18932
Publ.-Id: 18932