First order reversal curve Hall analysis of zero-field skyrmions on Pt/Co/Ta multilayers

Abstract

Magnetic skyrmions are non-trivial spin textures that resist external disturbances and are promising candidates for use in next generation spintronic devices. However, a major challenge in the realization of devices based on skyrmions is the stabilization of ordered arrangements of these spin textures under ambient temperature and zero applied field conditions. Multilayers of ferromagnetic materials (Co) interspersed with heavy metals with strong spin–orbit coupling (Pt and Ta), exhibit interesting properties, as the Dzyaloshinskii–Moriya interaction, which is an anti-symmetric exchange interaction that tilts the spins of neighboring layers, helps to stabilize skyrmions. In this work we study the formation and stabilization of magnetic skyrmions in Pt/Co/Ta films using a first order reversal curve (FORC) analysis, obtained from Hall effect measurements. The analysis of the FORC Hall diagrams was used to determine the intensity of the magnetic fields that should be applied to nucleate and stabilize skyrmions at remanence. Magnetic force microscopy images and micromagnetic simulations were compared to determine the correlation of the domain textures with the applied field and magnetic parameters of the multilayers.