Exchange bias energy in Co/Pt/IrMn multilayers with perpendicular and in-plane anisotropy

The magnetization reversal process in perpendicularly biased [Pt/Co]3/dPt[Pt/Co]3/dPt Pt/IrMn and in-plane biased Co/dPtCo/dPt Pt/IrMn multilayers with 0nm⩽dPt⩽1.2nm was investigated using Kerr magnetometry and Kerr microscopy. For the system with in-plane magnetic anisotropy, the exchange bias field decreases monotonically with Pt insertion layer thickness, while its coercivity remains constant. The samples with perpendicular magnetic anisotropy, on the other hand, exhibit maximum exchange bias and minimum coercivity for dPt=0.1nm. In both cases, the existence of large exchange bias fields correlates with a high domain density during magnetization reversal. The interface exchange coupling energy is larger for the in-plane biased films than for the perpendicularly biased multilayers.