Inverted magnetoresistance in dual spin valve structures with a synthetic antiferromagnetic free layer

Abstract

We report an oscillation of the giant magnetoresistance GMR ratio as a function of Ru layer thickness in the CoFe/Cu/ CoFe/Ru/CoFe SAF/Cu/CoFe/IrMn dual spin valve SV structure. A normal GMR with a positive sign is observed for the thickness of Ru providing a ferromagnetic interlayer exchange coupling IEC . The inverted GMR is observed for the thickness of Ru providing an antiferromagnetic IEC, which is consistent with IEC period across the Ru spacer as well as the electrical separation of the overall structure into two SVs connected in parallel.