Design, fabrication and 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 2 μm, a read gap of 0.25 μm, and a MR sensor height of 1 μm. The spin-valve sensor had a structure of 100 Å NiFe/25 Å Cu/22 Å Co/110 Å 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 1.5 μm showed linear, non-saturated signal response on a media with an areal moment as high as 1.25 memu/cm², yielding reasonably symmetrical signals with peak-to-peak amplitudes ranging from ~750 μV/μm to as high as ~1000 μV/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