In-depth resolution of the magneto-optical Kerr effect in ferromagnetic multilayers -: art. no. 224423

How does one determine the magnetization state and hysteresis loop corresponding to one of the ferromagnetic (FM) layers located at a given depth in a stack of FM/non-FM layers by means of the magneto-optical Kerr effect? For this purpose the representation of the Kerr effect in the complex rotation-ellipticity plane is introduced. A depth sensitivity function controlling the Kerr effect is defined and its dependence on the photon energy and angle of incidence is studied. A general way to determine the in-depth location of the FM layer, from which the Kerr signal originates, is proposed. In the case of a FM bilayer structure, previous proposed solutions are discussed within a unified formalism. For a system with three or more FM layers two approaches are proposed to extract selectively the magneto-optical signals originating at individual FM layers: the parallel Kerr vector and cascade numerical projection methods. These methods are successively checked experimentally on simple multilayer structures. Finally, on the basis of the developed approaches a readout solution for multivalued magneto-optical recording in a four-storage-layer structure is proposed.