Three dimensional magnetic flux concentrators with improved efficiency for magnetoresistive sensors

Three dimensional (3D) magnetic flux concentrators (FC) based on 7000-A-thick Co86Zr5Nb9 films were optimized for increased sensitivity in hybrid flux guide-magnetoresistive sensor structures. The vertical profile of the flux guide patterned by lift-off was replaced by a 3D structure where the sensor is recessed from the FC with a controlled edged slope defined by ion milling at controlled angles (20°, 45°, 60°, 75°, and 85°). In this work, spin valve linear sensors (3 × 14 μm2) with initial sensitivity of 0.084%/Oe were integrated with the flux guides patterned with these 3D tapered profiles. Optimized flux guides with 45° slope could increase the sensitivity up to 7.4%/Oe, corresponding to a concentrator flux gain of ∼100.