High frequency high field permeability of patterned Ni{sub 80}Fe{sub 20} and Ni{sub 45}Fe{sub 55} thin films

High frequency high field permeability of patterned Ni{sub 80}Fe{sub 20} and Ni{sub 45}Fe{sub 55} thin films was measured from lithographically defined toroids. Measurement frequency is up to 500 MHz and excitation field up to 5 Oe. Permeability rolloff is calculated from the inductance data. In this experiment, patterned widths range from 30 down to 0.5 {mu}m. Our data suggest that the rotational permeability measured at low field excitation is sufficient to predict high frequency characteristics. The rotational permeability decreases with decreasing patterned width. The 0.5 {mu}m wide permalloy device has {mu} of 80 and the Ni{sub 45}Fe{sub 55} 50. {copyright} 2001 American Institute of Physics.