Analogue Tuning of Magnetic Skyrmion Properties at Room Temperature in Ir/Fe/Co/Pt Multilayers

Magnetic skyrmions are robust nanoscale spin structures which have recently been discovered within several material systems. Their small size, topological stability, and ease of manipulation offer great promise for next-generation information storage devices. In the past year, several synchrotron-based experiments on multilayer films have revealed stable ~100 nm skyrmions at room temperature (RT). In order to systematically explore the viability of skyrmion-based nanoscale devices, it is timely to develop material systems offering inherent tunability of skyrmion properties. Here we describe the realisation of such a tunable RT skyrmion platform based on multilayer stacks of Ir/Fe/Co/Pt. We confirm the presence of nanoscale Neel skyrmions via established X-ray microscopy techniques, and further utilise magnetic force microscopy and Hall transport - hitherto unused for multilayer skyrmions - to investigate their evolution with magnetic field and sample composition. By varying the ferromagnetic layer composition and thickness, we demonstrate control over skyrmion size, density and ease of nucleation. We thus establish a platform for tuning and investigating properties of sub-50 nm RT skyrmions in a standard laboratory setting.