Exchange bias anisotropy on the dynamic permeability of thin NiFe layers

Abstract

30 nm permalloy thin films have been grown by sputter deposition with and without an 8 nm IrMn exchange bias layer. The microwave permeability of these layers has been investigated in the 100 MHz–3 GHz range with a permeameter based on a microstrip cell, applying an external field along the easy axis. A comparison between the bias field deduced from magneto-optical Kerr effect measurements and a fit of the dynamic permeability spectra is made. Significant hysteresis effect on the microwave permeability of the biased sample is observed and modeled.