Write induced magnetic field in spin-valve heads

The magnetic field at a spin valve (SV) element is measured by exciting the inductive write head with a pulse current. The measured write-induced magnetic field can be used as an indicator of write-induced stability. A piggyback type SV head and a merged type SV head are compared in terms of the magnetic field at the SV. While the write-induced magnetic field of the merged head saturates at 40 mA as current increases, that of piggyback head does not saturate even at 120 mA. The method reported here can be used to evaluate the SV magnetic performance and to obtain the yoke saturation curve of the inductive write head in a merged SV head.