The contribution of x-ray specular reflectometry to the oxygen-induced magnetic properties in Pt/Co/AlOx
Résumé
Two key parameters were analyzed in Si/SiO/Pt/Co/AlOx: the oxidation time of the Al layer resulting in AlOx, and the ex situ annealing temperatures varied in the 15 and 55 s and 20, 300, and 450 °C ranges, respectively. For intermediate annealing temperatures (∼300 °C), the quantitative analysis of specular reflectometry data shows that the progressive oxidation of layers by increasing the oxidation time goes along with an improvement of the homogeneity of the alumina layer. This outcome casts new light on the temperature dependence of magnetic properties of the samples. The remarkable temperature variation of the coercive field, extracted from extraordinary Hall effects in the 5-300 K range, is associated with structural change due to Co-oxygen bondings, which leads to strong pinning of Co spins in the low temperature regime.
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