Copper spacer thickness dependence of the exchange bias in IrMn/Cu/Co ultrathin films

The exchange-bias, H-EB and coercivity, H-C of IrMn/Cu(t(Cu))/Co films have been investigated as a function of the Cu spacer thickness, t(Cu) before and after magnetic annealing. A large increase of H-EB and a significant decrease of H-C with the treatment were observed for the samples with t(Cu) <= 1.0 nm. H-C(t(Cu)) and H-EB(t(Cu)) showed a general trend of rapid decrease for all samples. The phenomenological models used to derive the anisotropy and exchange coupling parameters from the magnetization data indicated that the antiferromagnetic part of the interface is fully spin-compensated for the as-made films and nearly uncompensated for the treated ones. The annealing, despite the H-EB and H-C changes, did not alter the Co anisotropy but only improved the interfacial IrMn spins alignment. (c) 2007 Elsevier B.V. All rights reserved.