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The magnetization reversal of magnetic multilayers with spin-valve like characteristics, patterned into an array of parallel stripes, was structurally and magnetically analyzed, in detail, via x-ray scattering, magnetometry, and polarized neutron reflectivity. Each stripe contains a multiple repetition of the layer sequence [Fe/Cr/Co/Cr]. X-ray and neutron scattering maps of the patterned multilayer show rich details resulting from the superposition of Bragg peaks representing the lateral in-plane periodicity and the out-of-plane multilayer period. Detailed analysis of specular and off-specular polarized neutron intensity was used to ascertain the antiparallel alignment of the Co and Fe magnetization within the kink region of their combined hysteresis loop between the coercive fields of Fe and Co layers. This includes also an examination of domain formation and inter- as well as intra-stripe correlation effects upon magnetization reversal. Our combined study shows that the shape induced anisotropy via patterning is capable of overriding the four-fold crystal anisotropy but is unable to eliminate the ripple domain state of the Co layers, already present in the continuous multilayer. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJ) have become of strategic importance due to the large tunneling magnetoresistance ratio (TMR) that they can achieve at room temperature. The largest TMR values observed until now were recorded in MTJs with MgO barriers and CoFeB electrodes after annealing of the junction above the recrystallization temperature of the amorphous CoFeB layers. We have used x-ray reflectivity combined with polarized neutron reflectivity to characterize the structure and the magnetism of [Co60Fe20B20/MgO]14 multilayers, where the MgO layers were prepared by different methods and annealed at different temperatures. We have found that the MgO preparation method as well as the annealing temperature play a significant role in the systems. A gradient in thickness together with a variation of the scattering length density along the multilayer stacks induce a process of underoxidation or overoxidation, strictly dependent on the MgO production method. [ABSTRACT FROM AUTHOR]

A new neutron reflectometer SuperADAM has recently been built and commissioned at the Institut Laue-Langevin, Grenoble, France. It replaces the previous neutron reflectometer ADAM. The new instrument uses a solid state polarizer/wavelength filter providing a highly polarized (up to 98.6%) monochromatic neutron flux of 8 × 104 n cm-2 s-1 with monochromatization Δλ/λ = 0.7% and angular divergence Δα = 0.2 mrad. The instrument includes both single and position sensitive detectors. The position sensitive detector allows simultaneous measurement of specular reflection and off-specular scattering. Polarization analysis for both specular reflection and off-specular scattering is achieved using either mirror analyzers or a 3He spin filter cell. High efficiency detectors, low background, and high flux provides a dynamic range of up to seven decades in reflectivity. Detailed specifications and the instrument capabilities are illustrated with examples of recently collected data in the fields of thin film magnetism and thin polymer films. [ABSTRACT FROM AUTHOR]