[Ni/Mn] superlattice-based spin-valves with high thermal stabilities

Abstract

Ni/Mn superlattice-based spin-valve films were fabricated by de sputtering method. Coercivity (H-c) of the pinned layer and exchange coupling field (H-ex) between the pinned layer and pinning Ni/Mn superlattice with an antiferromagnetic phase were investigated in order to optimize the deposition conditions and annealing profess. The thickness of each layer was controlled by deposition time. The H-ex and H-c of Ni/Mn superlattice-based spin-valves increased gradually with the number of annealing cycles and number of bilayers. At the Ni composition of 38 at. % for the annealing time of 12 hours, the largest H-ex and H-c of glass/[Ni/Mn](80)/NiFe(60 Angstrom)/Cu(30 Angstrom)/NiFe(60 Angstrom) spin-valves are 305 Oe and 245 Oe, respectively. However, the magnetoresistance (MR) ratio is small, due to the shunting effect of Ni/Mn superlattice and the interdiffusion between NiFe and Cu.