Non-linear interplay between exchange-bias-induced unidirectional anisotropy and oblique-deposition-induced uniaxial anisotropy

A systematic investigation of the non-linear interplay between the uniaxial magnetic anisotropy induced by oblique deposition and the unidirectional magnetic anisotropy induced by exchange bias coupling in NiFe/MnIr bilayers was performed. It was found that depending on the oblique angle, the uniaxial anisotropy induced by oblique deposition may play a vital role in defining the orientation of exchange bias. In particular, when the oblique angle is in the range from 31 degrees to 45 degrees, the oblique-deposition-induced anisotropy is large enough to reorient the easy axis of exchange bias to the direction perpendicular to the deposition field leading to the appearance of double-shifted loops. When the oblique angle is less than 30 degrees or higher than 45 degrees, normal exchange bias is observed with typical behavior. The dynamic permeability spectra are also presented and discussed in conjunction with the static magnetic properties. (C) 2013 AIP Publishing LLC.