No abstract

We have investigated the magnetic structure of a Sr2FeMoO6 single crystal by X-ray magnetic circular dichroism at the L2,3 edges of Fe and Mo sites. The spin magnetic moments we find on Fe (3.05µB) and Mo (−0.32µB) give, for the first time, a direct confirmation of their ferrimagnetic ordering. The presence of a finite spin moment on Mo together with only very small orbital moments on both Fe and Mo confirms that the predicted half-metallicity of the Sr2FeMoO6 compound is due to a configuration with five localized d electrons forming a high-spin moment on Fe and one s antiparallel delocalized electron shared between the Mo and the other sites.

SmN is ferromagnetic below 27 K, and its net magnetic moment of 0.03 Bohr magnetons per formula unit is one of the smallest magnetisations found in any ferromagnetic material. The nearzero moment is a result of the nearly equal and opposing spin and orbital moments in the 6 H 5/2 ground state of the Sm 3+ ion, which leads finally to a nearly complete cancellation for an ion in the SmN ferromagnetic state. Here we explore the spin alignment in this compound with X-ray magnetic circular dichroism at the Sm L 2,3 edges. The spectral shapes are in qualitative agreement with computed spectra based on an LSDA+U (local spin density approximation with Hubbard-U corrections) band structure, though there remain differences in detail which we associate with the anomalous branching ratio in rare-earth L edges. The sign of the spectra determine that in a magnetic field the Sm 4f spin moment aligns antiparallel to the field; the very small residual moment in ferromagnetic SmN aligns with the 4f orbital moment and antiparallel to the spin moment. Further measurements on very thin (1.5 nm) SmN layers embedded in GdN show the opposite alignment due to a strong Gd-Sm exchange, suggesting that the SmN moment might be further reduced by about 0.5 % Gd substitution.

No abstract

Decomposition of sputtered PtOx layers has been studied by x-ray absorption spectroscopy. X-ray absorption fine structure measurements demonstrated that as-deposited films possess a composition of PtOx (x=1.1–1.7). Upon annealing, the metallic platinum phase is formed. The formation of the metallic Pt phase starts at very early stages of the decomposition process. The decomposition is not monotonic and slows down at the final stage. The structure at intermediate stages of decomposition is a mixture of the starting phase and metallic Pt.