Interphase exchange effects in CoPt/Co bilayer thin films

Abstract

The condition of the interphase interface in model exchange-spring CoPt/Co bilayers was correlated with the magnetic response. Polycrystalline bilayer samples of 16.7-nm Co and 25-nm L10-type CoPt were fabricated and subsequently annealed to vary the condition of the interphase interface. Although the thickness of the soft phase component exceeded that for ideal (i.e. completely reversible) interlayer exchange coupling, this thickness allowed correlations between the interfacial condition and the magnetic quality of the exchange spring components to be observed and quantified via magnetic recoil measurements. Annealing the bilayers at 300°C for 20 min produced a 63.0% increase in the coercivity of the soft component, while at the same time the coercivity of the hard component was decreased by 18.5%.