Influence of thickness on magnetic properties and microwave characteristics of NiFe/IrMn/NiFe trilayers

Abstract

Exchange-bias effect is effective in in creasing the ferromagnetic resonance frequency of soft magnetic thin films. This paper studies the static magnetic properties and microwave characteristics of Ni81Fe 19/Ir25Mn75/Ni81Fe19 trilayers with various Ni81Fe19 and Ir25Mn 75 thicknesses. With an ultrathin Ir25Mn75 interlayer, the trilayer has an enhanced effective damping without exchange-bias effect. The exchange-bias effect is observed with a thicker Ir 25Mn75 interlayer. The two resonance frequencies in permeability spectra are due to the different interfacial exchange couplings at the two interfaces of trilayers, and they increase with decreasing Ni 81Fe19 layer thickness. © 2011 IEEE.