Fundamental limits on the z-resolution of ion beam patterning of magnetic multilayers

Abstract Ion beam etching (i.e. ion milling) is the preferred patterning method for metallic magnetic multilayers. We explore the extendibility and fundamental limits of the technique with regard to z-resolution (i.e. etched depth). We studied the atomic relocation in Ni–Cu and Co–Cu multilayers under Ar+ bombardment, using molecular dynamics simulations. The atomistic mechanisms upon impact are significantly different for the two systems, especially on the monolayer scale: Ar bombardment of Co on Cu is found to lead to dewetting, while bombardment of Ni on Cu is found to lead mostly to formation of an interfacial alloy due to relocated atoms.