Design, Fabrication & Testing of Spin-Valve Read Heads for High Density Recording

Spin-valve sensors of the type Nife/Cu/Co have been designed for optimal biasing behavior and successfully incorporated into a gigabit-type shielded read head configuration with a read trackwidth of 2µm, a read gap of 0.25µm, and a MR sensor height of 1µm. The spin-valve sensor had a structure of 100Å NiFe/25Å Cu/22Å Co/110Å FeMn, and yielded a net spin-valve coefficient of ~3.5% at the completion of head processing. Uniform field testing of the read heads after wafer fabrication and lapping showed quiet and stable spin-valve response with near optimal bias performance. Recording tests of the read heads at a head-disk clearance of 1.5µin showed linear, non-saturated signal response on a media with an areal moment as high as 1.25memu/cm2, yielding reasonably symmetrical signals with peak-to-peak amplitudes ranging from ~750µV/µm to as high as ~1000µV/µm of read trackwidth. Linear density rolloffs and microtrack profiles have also been studied, and results showed behaviors closely agreeing with design targets for high density recording operations. © 1994, American Institute of Physics