Direct observation of topological Hall effect in Co/Pt nanostructured films

A method consisting of simultaneous measurements of a Hall effect and a magneto-optic Kerr effect is used to study a topological Hall effect in thin ferromagnetic films. The method is based on the idea that the values of the topological effects are different at dc and optical frequencies. The topological Hall effect in the artificial lattices of magnetic bubbles in nanostructured Co/Pt multilayers with perpendicular magnetic anisotropy is investigated using this method. The Lorentz transmission electron microscopy measurements demonstrate skyrmionic topology of the magnetic bubbles. The measured topological Hall effect is proportional to the skyrmion density in the system.