Characterizing Curvature in Heat-Assisted Magnetic Recording Using Spin-Stand Imaging

In an ideal magnetic recording system, individual bits would be recorded as rectangular magnetic domains in the recording media, but in reality, the transitions from one bit to the next are curved due to practical geometry considerations. This is particularly true in heat-assisted magnetic recording, where the shape of the bits is defined primarily by the approximately circular thermal spot produced in the media by the laser near-field transducer. Since this curvature in the transition profiles can degrade the signal-to-noise ratio and bit error rate of the read signal, an accurate metrology tool for characterizing the curvature produced by various head and media designs is essential. Here, we present a method of aligning read signals from trimmed tracks at a range of cross-track positions to produce a 2-D map of the magnetic patterns recorded in the media. From these data, metrics characterizing the transition curvature (e.g., the radius of curvature at the track center) can be extracted.