Interface-induced optical effects in magnetic two- and three-layer films

Multilayer planar nanostructures formed by ferromagnetic and heavy metals can reveal unique properties governed by their composition and geometry. The main role in their formation belongs to the interfacial spin–orbit interaction leading to specific magnetic distributions and behavior at the nanoscale. Here we present a complex analysis of magneto-optical effects in nanolayered films composed of different combinations of cobalt nanolayers with tantalum and platinum ones. Magnetic force microscopy studies confirm inhomogeneous magnetization distribution in $\left(\mathrm{Ta},\mathrm{Pt}\right)/\mathrm{Co}\mathrm{and}\left(\mathrm{Ta},\mathrm{Pt}\right)/\mathrm{Co}/\left(\mathrm{Ta},\mathrm{Pt}\right)$ films, which can be described in terms of magnetic ripple domain or chiral structures. Experiments on the Brillouin light scattering directly confirm the appearance of the interface Dzyaloshinskii-Moriya interaction in the studied films, the effect increases with the structural asymmetry. Finally, interface-sensitive second harmonic generation (SHG) reveals odd in magnetic field SHG intensity effect for the longitudinal geometry of the applied dc magnetic field that is absent for homogeneously magnetized structures.