Method of characterizing exchange coupling for magnetoresistive sensor

摘要

An MR sensor includes an MR layer and permanent magnets defining an active area on the MR layer. A bi-layer test structure is fabricated with a permanent magnet layer deposited on a substrate and an MR layer deposited on the permanent magnet layer. If desired, a SAL may be deposited prior to deposition of the permanent magnet layer. A DC magnetic field is applied to the bi-layer test structure, and the strength of the DC magnetic field is varied. During application of the DC magnetic field, the magnetic response of the bi-layer test structure is measured to determine a hysteresis loop of the bi-layer structure. The exchange coupling between the permanent magnet layer and the MR layer is characterized by a point of inflection identified on the measured hysteresis loop.