Layer-resolved magnetometry of a magnetic bilayer using the magnetoopticalKerr effect with varying angle of incidence

We determined the hysteresis loop of each layer in a magnetic bilayer of Ni Fe-SiO2-CoFe using the magneto-optical Kerr effect. Our method utilizes the fact that varying the angle of incidence of the optical beam changes the m agnitude and sign of the polarization rotation signal contributed by each l ayer to the total signal. The magneto-optical signal of each layer varies d ifferently with the angle of incidence, enabling us to determine the hyster esis loop of each. We measured the hysteresis loop of the bilayer for a ran ge of angles of incidence, and from these loops determined the magnetizatio n of the individual layers. We found that the magnetization of the soft NiF e layer coupled strongly to the CoFe layer for SiO2 interlayer thicknesses of <2 nm. The NiFe loop shears with decreasing interlayer thickness, increa ses in coercivity, and develops a two-stage switching behavior at an interl ayer thickness of 1 nm. (C) 1999 American Institute of Physics. [S0021-8979 (99)65908-4].