A new method for high-frequency characterization of patterned ferromagnetic thin films

A new high-frequency method is presented for patterned ferromagnetic thin film characterization. Parasitic effects, which often overwhelm the signal from patterned ferromagnetic structures, are significantly reduced through an on-chip interference process. As a result, measurement sensitivity is greatly improved in comparison with conventional on-chip transmission line ferromagnetic resonance (FMR) methods. Algorithms are given to extract the complex permeability and FMR linewidth of ferromagnetic materials from scattering parameters obtained with the method. An on-chip 10 GHz structure was fabricated and experimentally demonstrated ∼20 dB parasitic effect cancellation efficiency. A patterned Permalloy (Py) array with 180 stripes is measured. Each stripe is 100 nm thick, 2 μm wide, and 20 μm long. The FMR frequency of the patterned Py thin films was tuned with an external static magnetic field. With a 676 G bias field, the obtained FMR frequency and linewidth are 9.68 and 1.4 GHz, respectively. These resu...