Polarized neutron reflectivity investigation of periodic magnetic rings

Magnetic ring structures are of particular interest, due to stable remanent configurations such as the vortex state, which have potential in future magnetic random access memory (MRAM) applications. Here we report results on the first experimental study of periodic ring arrays using off-specular polarized neutron reflectivity (PNR). The experiments were performed on a 7.5 mm x 5 mm NiFe array with an average ring diameter of 3.2 mu m, 0.7 mu m width, 25 nm thickness, and separation of 5.6 mu m. Using polarization analysis, a spin dependent diffraction of reflected and transmitted neutron beams were investigated as a function of external applied field.