Magnetostatic spin waves in ferromagnetic microstructures

Alexander Kozhanov
UCSB Physics

A current technology drive, directed toward future signal processing and logic devices, attempts to introduce spin degrees of freedom as an alternative, complement or companion to semiconductor charge based electronics. But, spin waves can transfer spin information and have the potential for spin control without directly moving charge. Microwave devices like delay lines, filters and resonators based on magneto-static waves in insulating ferrimagnetic materials like yttrium-iron garnet (YIG) have long been explored and developed. However, future micro and nano scale spin wave logic devices may benefit from exploiting ferromagnetic metals that are more easily deposited, processed and nanofabricated than ferrimagnetic oxides. Further, ferromagnetic metals, like CoTaZr and CoFe, have nearly an order of magnitude larger saturation magnetization than typical ferrimagnets and will support higher, shape defined, zero magnetic field resonances and permit intrinsically faster response. We discuss experimental results obtained from various spin waveguide structures:

• Spin wave dispersion of the lowest order modes.

• "Tunneling" through large gaps produced by focused ion beam etching, characteristic of the long range dipolar interactions that support these waves.

• Modes in ferromagnetic tubes fabricated by simultaneously wrapping magnetic material around proximate ends of the shorted coplanar waveguides.

• Modes and spin wave scattering in a ferromagnetic cross.

This work is supported by NERC via the Nanoelectronics Research Initiative (NRI), by Intel Corp. and UC Discovery at the Western Institute of Nanoelectronics (WIN) Center.