Enhanced GMR ratio of dual spin valve with monolayer pinned structure

A new type of dual spin valve (DSV) structure with enhanced giant magnetoresistance (GMR) ratio is proposed, and the performance is characterized by the prototype read heads. The bottom part of DSV is kept as a synthetic pinned structure and only the top part adopts a monolayer pinned structure. The top monolayer pin DSV (TM-DSV) showed three percentage points higher GMR ratio and 20% higher ΔR value. After the mechanical lapping process, the monolayer pinned layer can be stabilized by not only sense current but also large stress induced anisotropy due to Villari effect. After the quantitative analysis, the induced stress is measured to be about 4.2×10⁹ N/m². The bias point was tuned by adjustment of Cu spacer layer thickness using the RKKY interaction between pinned layer and free layer. There is no reliability concern related to the monolayer pinned structure. In a perpendicular magnetic recording system, TM-DSV technology could successfully demonstrate the output of 35.5 mV/μm and ∼170 Gbits/in² density feasibility.