DESIGN AND OPERATION OF SPIN-VALVE SENSORS

Two types of patterned, unshielded Giant MagnetoResistance (GMR) spin valve sensors have been fabricated: nano-layered NiFe/Co/Cu/Co/NiFe an d simpler NiFe/Cu/Co spin valves. GMR values of 7.6% for AH = 10 Oe we re measured for the nano-layered structures on coupons. Transfer curve s in uniform fields were obtained and were in agreement with theoretic al expectations. The sensors were highly linear and well biased. Optim um biasing of the free layer in the spin valve sensor has new features over that in AMR sensors. These were explored in shielded as well as unshielded spin valves using micromagnetic simulation.