Exchange bias effect and anisotropy analysis of FM/AF bilayers

The exchange bias effect of NiFe–MnPd bilayers and a new system Fe–MnPd bilayers was analyzed. Through fitting the in-plane angular dependence of the exchange bias field Hex and the coercivity Hc obtained by magneto-optical Kerr effect (MOKE), the in-plane anisotropies of the two systems were obtained. We found large additional higher order anisotropies (uniaxial and four-fold) in the system due to ferromagnet (FM)–antiferromagnet (AF) exchange bias coupling. These anisotropies show a linear dependence on the inverse FM thickness indicating their interfacial origin caused by exchange bias effect. The thickness dependence of the exchange bias fields Hex and the coercivity Hc also exhibited a linear dependence on the inverse FM layer thickness.