Exchange biasing field of NiFe/[IrMn-Mn]/CoFe multilayers depending on Mn content

Abstract

Exchange bias by inserting a submonolayer of Mn between two neighboring IrMn layers in NiFe/[IrMn-Mn]/CoFe multilayers was investigated. As-deposited CoFe pinned layers with an [IrMn-Mn] layer resulted in larger exchange biasing field (H-ex) and blocking temperature (T-b) than when pure Ir22Mn78 was used. H-ex and T-b improved with content of 76.8-78.1 vol % Mn, but H-ex and T-b of NiFe/IrMn/CoFe dropped considerably with addition of more than 0.6 vol % Mn. The H-ex obtained for as-grown two multilayer samples with 77.5 and 78.7 vol % Mn, were 259 and 150 Oe, respectively. In the case of IrMn with 77.5 vol % Mn, H-ex increased to 475 Oe at 350 degreesC but decreased to 200 Oe at 450 degreesC. The magnetic properties and thermal stabilities of the NiFe/[IrMn-Mn]/CoFe multilayer were enhanced by suitable additions of Mn. In applications where higher H-ex and T-b were required, the proper contents of Mn could be used. (C) 2004 American Institute of Physics.