Interaction between exchange-bias systems in Ni₈₀Fe₂₀∕Fe₅₀Mn₅₀∕Co trilayers

The coupling effect between two adjacent exchange bias systems in a trilayer structure was studied. NiFe∕FeMn∕Co trilayers were prepared in a controlled field to induce conventional biasing in the bottom NiFe∕FeMn system, but not in the top FeMn∕Co structure. By comparing the magnetic behavior of as-deposited samples with that after field cooling from high temperature, we probed the interactions between the two biased systems through a common antiferromagnetic spacer. The temperature dependences of exchange bias fields and coercivities indicated that exchange bias was not simply an effect between a ferromagnet and an antiferromagnet across the interface; the bulk of the antiferromagnet layer, together with the presence of the second biasing system, were required to account for the final behavior of the whole trilayer exchange bias structure.