The effects of a microbridge buffer layer on the sensitivity of a local ferromagnetic resonance probe

A new fabrication technique for a near-field microwave probe that greatly improves the sensitivity is presented. This design and fabrication has enabled quantitative measurements (with a probe as small as micron scale) that were not previously possible, such as ferromagnetic resonance in media with relatively small permeability, large damping, and high anisotropy (H-K). The new method uses a focused ion beam to deposit and lithographically define a SiO2 or Pt buffer between the inner and outer conductors of a microcoax. A thin Cu film is then deposited, after which the Cu is etched in the field, preserving the Cu over the buffer to complete a microbridge. The buffer layer results in surface smoothness on the order of 10 nm at the top and bottom (Cu/buffer) surfaces of the Cu. (C) 2008 American Institute of Physics.