Angular dependence of exchange coupling in NiFe/spacer/IrMn trilayer structures

Angular dependence of exchange coupling for NiFe/Cu/IrMn trilayer thin films were examined as a function of the Cu spacer thickness. The exchange coupling field and the coercivity showed an exponential decay, respectively, with the thickness of the Cu spacer. The exchange coupling field remained up to a Cu spacer thickness of 6 A, indicating the existence of exchange coupling through the spacer layer. As the Cu spacer thickness increases, angular variation of exchange coupling field shifted from asymmetric to symmetric with respect to the origin of coordinate and uniaxial symmetry of coercivity changed into mixed shape of uniaxial and four-fold-like symmetry.