Engineering of the anisotropy and Dzyaloshinskii-Moriya interaction energies in Pt-Co and Pt-Co-Cu heterostructures

It has previously been shown that perpendicular magnetic anisotropy is increased in Pt-Co-Pt structures by placing a Cu spacer between the top, diffuse Co-Pt interface.\footnote{S. Bandiera et al, \textbf{Appl. Phys. Lett.} 100, 142410 (2012)} However, including a spacer layer increases interfacial asymmetry in the system: a prerequisite for a strong Dzyaloshinskii-Moriya interaction (DMI) which governs helical spin structures such as skyrmions and chiral domain walls.\footnote{S. Emori et al, \textbf{Nature Mater.} 12, 611-616 (2013)} We show that the increased asymmetry significantly enhances DMI strength in Pt-Co-Cu-Pt heterostructures as compared to corresponding Pt-Co-Pt systems. We further show that one can control the characteristic length scales governing domain width by engineering the magnetostatic, anisotropy, and DMI energies in heavy-metal/ferromagnet heterostructures. These structures may provide insight into engineering the size of skyrmions in spintronic devices.