Magnetic domain wall substructures in Pt/Co/Ni/Ir multi-layers

Abstract

We examine the substructures of magnetic domain walls (DWs) in [Pt/(Co/Ni) M/Ir] N multi-layers using a combination of micromagnetic theory and Lorentz transmission electron microscopy. Thermal stability calculations of Q = ± 1 substructures [2 π vertical Bloch lines and DW skyrmions] were performed using a geodesic nudged elastic band model, which supports their metastability at room temperature. Experimental variation in strength of the interfacial Dzyaloshinskii-Moriya interaction and film thickness reveals conditions under which these substructures are present and enables the formation of a magnetic phase diagram. Reduced thickness is found to favor Q = ± 1 substructures likely due to the suppression of hybrid DWs. The results from this study provide an important framework for examining 1D DW substructures in chiral magnetic materials.