J. Marcus

The contribution of x-ray specular reflectometry to the oxygen-induced magnetic properties in Pt/Co/AlOx

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.

Magnetotransport properties of the purple bronze KMo6O17

Abstract The electrical resistivity of the purple bronze KMo 6 O 17 has been studied between 2K and 100 K with pulsed magnetic fields up to 30 Teslas. Several anomalies are found on the curves Δϱ/ϱ(B) at different temperatures and ϱ(T) for different fields. A phase diagram which may show a field displaced density wave instability and field induced transitions is proposed.

Effect of high magnetic fields on the charge density wave properties of KMo6O17

Abstract The electrical resistivity of the purple bronze KMo6O17 has been studied between 2 and 88 K with pulsed magnetic fields up to 35 T. Several anomalies are found on the curves Δρ/ρ(B) at different temperatures. The low field results are compared with previous measurements of susceptibility and magnetization. A phase diagram which may show a field displaced charge density wave instability and field induced transitions is proposed.