A Nondestructive Local FMR Probe for On-Disk Media Characterization

High-frequency characterization of perpendicular media is demonstrated on disk with a novel nondestructive local probe. The probe is micron-scale and has high bandwidth. We measure the permeability of the soft underlayer (SUL) and observe its ferromagnetic resonance (FMR). We extract physical parameters that cannot typically be measured on disk, such as FMR frequency, anisotropy field, H_K, saturation magnetization, M_S, and damping alpha in good agreement with independent measurements. Media of arbitrary form factor can be characterized and any location can be probed with spatial resolution that scales with the size of the probe "tip."