Magnetic coercivity control via buffer layer roughness in Pt/Co multilayers

Abstract

Magnetic properties of thin metallic films are strongly dependent on the growth parameters. Therefore, fine-tuning these parameters is necessary to produce multilayers with specific physical properties required by various applications. Here, we present an efficient approach to tune the coercive field of magnetron sputtered Co/Pt multilayers using Au underlayer with variable thickness. We were able to control the interfacial roughness of the layers in the stack via the change of the Au underlayer thickness due to its island-like growth mechanism (Volmer-Weber mode). As the nominal thickness of Au increased, the islands grew in larger lateral size, resulting in higher surface roughness of the underlayer, which was transferred to subsequent interfaces. Magnetization measurements showed additional magnetic anisotropy promoted by this mechanism. Variating the thickness of the Au layer up to 20 nm, we changed the coercive field in the range from ∼ 200 Oe to ∼ 1100 Oe while maintaining a nearly constant saturation magnetization. Presented results demonstrate the possibility to precisely design magnetic properties of metallic multilayers for applications via buffer layer roughness engineering.