Layer-resolved vector magnetometry using generalized magneto-optical ellipsometry

We demonstrate the ability of a single magneto-optical reflection experiment to achieve layer-resolved vector magnetometry in multilayer films. For this purpose, we designed, fabricated, and measured a set of epitaxial ferromagnetic/non-magnetic/ferromagnetic heterostructure multilayer samples that exhibit in-plane uniaxial anisotropy and a tunable ferromagnetic interlayer coupling strength through the non-magnetic interlayer. By means of generalized magneto-optical ellipsometry measurements, we obtain the magnetization angles of the two different ferromagnetic layers independently as a function of the applied field. Hereby, we observe that the magnetization switching of one layer can trigger a discontinuous shift of the magnetization angle in the second layer if ferromagnetic interlayer coupling is present. Moreover, we reproduce the obtained behavior using a model of two coupled macrospins, which corroborates even the unexpected aspects of our experimental results and thus reinforces the sensitivity and reliability of our experimental layer-resolved vector magnetometry.