Write induced instability in spin-valve heads

The output amplitude variation of a spin-valve (SV) head, induced by a write operation, was investigated. The characteristics well depended on the sign of the write current just before a readback process started. It indicated that the write-induced instability should come from a magnetization hysteresis of somewhere magnetic materials. The magnetic core, which consisted of shields and a yoke, was under suspicion as a candidate of the hysteretic origin by sense current, medium and external field excitation tests. Magnetization modeling of a head core revealed a possible mechanism of the instability, which was a shield-related hysteresis.