Effects of in situ magnetic field application and post-deposition magnetic annealing on sputtered Fe50Mn50/Ni80Fe20 bilayers

Abstract

Effects of in situ magnetic field deposition and post-deposition magnetic annealing on the exchange field and coercivity of Fe50Mn50(200 Å)/Ni80Fe20 bilayers over a range of 40-120 Å Ni80Fe20 thicknesses were investigated. A large increase in coercivity and exchange field was observed in samples that were annealed at 230°C for 15 min in vacuum. The structure with 80 Å Ni80Fe20 thickness was found to exhibit maximum exchange field in the range of thickness investigated. The non-monotonic dependence of exchange bias with ferromagnetic layer thickness suggests the important role played by the microstructure of the Fe50Mn50 antiferromagnetic AF layer. These phenomena are discussed in relation to surface roughness, grain sizes, diffusion and magnetic domains. © 2002 Elsevier Science B.V. All rights reserved.