Micron scale ferromagnetic tubes placed on the ends of ferromagnetic CoTaZr spin waveguides are explored in order to enhance the excitation of Backward Volume Magnetostatic Spin Waves. The tubes produce a closed magnetic circuit about the signal line
of the coplanar waveguide and are, at the same time, magnetically contiguous with the spin waveguide. This results in a 10 fold increase in spin wave amplitude. However, the tube geometry distorts the magnetic field near the spin waveguide and relatively high biasing magnetic fields are required to establish well defined spin waves. Only the lowest (uniform) spin wave mode is excited.
Resonant coupling of coplanar waveguides is explored by wrapping proximate shorted ends of the waveguides with micron size ferromagnetic Co90Ta5Zr5 tubes. Ferromagnetic resonance and up to 7 outer surface modes are identified. Experimental results fo
r these contorted rectangular tubes are in good agreement with micromagnetic simulations and model calculations of magnetostatic modes for an elliptical ferromagnetic tube. These results indicate that the modes are largely determined by tube topology and dimensions but less so by the detailed shape.
Magnetostatic spin wave dispersion and loss are measured in micron scale spin wave-guides in ferromagnetic, metallic CoTaZr. Results are in good agreement with model calculations of spin wave dispersion. The measured attenuation lengths, of the order
of 3um, are several of orders of magnitude shorter than that predicted from eddy currents in these thin wires. Spin waves effectively tunnel through air gaps, produced by focused ion beam etching, as large as 1.5 um.
