Magnetoresistance of antiferromagnet CoFe/Ru/CoFe/IrMn top spin valve with thermal stability

Abstract Thermal stability and magnetoresistive properties of synthetic antiferromagnet spin valves (SAF/SV) having the Ta20/NiFe20/CoFe20/Cu22/CoFe25/Ru5/CoFe22/IrMn40/Ta20 (in A) structure were investigated. The SAF/SV annealed for a 1 h at 200°C exhibits a magnetoresistance (MR) ratio of 8.8%, an effective exchange coupling field (Heex) of 1170 Oe, and an antiferromagnetic (AF) saturation field (Hs) of 5200 Oe at room temperature. Heex varies in approximately a 1/tAP2 (tAP2 is the thickness of CoFe layer adjacent to antiferromagnet layer). Heex and MR ratio are stabilized after the first annealing cycle, and it is thought that this SAF/SV reveals higher thermal stability.