Three Dimensional Magnetic Flux Concentrators With Improved Efficiency For Magnetoresistive Sensors

Three dimensional (3D) magnetic flux concentrators (FC) based on 7000-angstrom-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 degrees, 45 degrees, 60 degrees, 75 degrees, and 85 degrees). In this work, spin valve linear sensors (3 x 14 mu m(2)) with initial sensitivity of 0.084%/Oe were integrated with the flux guides patterned with these 3D tapered profiles. Optimized flux guides with 45 degrees slope could increase the sensitivity up to 7.4%/Oe, corresponding to a concentrator flux gain of similar to 100. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556946]