[en] An atomic-scale quantitative analysis of the structural and magnetic properties of surfaces, interfaces and complex nanostructures is of fundamental relevance for the development of new materials for spintronics. Studies of buried magnetic interfaces and depth-resolved measurements in layered magnetic nanostructures are particularly challenging, and the combination of conversion electron Mössbauer spectroscopy and/or nuclear resonant scattering of synchrotron radiation with isotope-enriched probe layers can be a powerful tool in this field. The potential offered by the application of isotope-selective measurements for the study of Fe-based layered magnetic nanostructures is illustrated with our recent results on the investigation of depth-dependent spin structures and interfacial interdiffusion in exchange-biased ferromagnetic/antiferromagnetic bilayer systems and of an epitaxial magnetic system with perpendicular magnetic anisotropy, obtained from samples prepared with ultrathin ⁵⁷Fe probe layers placed at different depths during the growth processes, via molecular beam epitaxy or sputtering deposition. - Highlights: • The potential of using ⁵⁷Fe probe layers for depth-resolved studies is illustrated. • Three studies of layered magnetic nanostructures by CEMS and NRS are described. • Direct evidence of depth-dependent spin rotation in exchange biased Fe/MnF₂. • FeCo epitaxially grown on Rh(0 0 1) at 300 K shows a chemically sharp interface

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[en] In this work, the initial stages of oxidation of the U4Zr2Nb alloy in O₂ atmosphere were studied in-situ, in ultrahigh vacuum, by X-ray photoelectron spectroscopy (XPS), an advanced surface-sensitive technique. After several hours of Ar⁺ion-sputtering to surface cleanness, the O₂ exposures was realized on the sample at room temperature. The evolution of oxide film formed on the sample surface was followed by XPS measures, by using Mg K_α radiation of 1253.6 eV and a CLAM-2 (Vacuum Generator) electron energy analyzer. The changes of U 4f, Nb 3d, Zr 3d and O 1s photoemission peaks with O₂ exposure indicate that the adsorption of oxygen on the U4Zr2Nb alloy surface leads to fast formation of UO₂. The alloying elements show slower oxidation and different compounds are observed in Nb 3d spectra analysis. This work shows an expressive enlargement of Nb 3d peak at 100 Langmuir exposure, indicating the formation of Nb₂O₅ and NbO in the oxide. On the other hand, the binding energy of Zr 3d suggests that the ZrO₂ formation is stable as well as uranium dioxide. (author)

[en] Gadolinium-doped hydroxyapatite (HA-Gd) nanorods have become promisor theranostic nanoparticles for early stage cancers as radioisotope carriers able to act in the treatment and multi-imaging diagnosis by single photon emission computed tomography and magnetic resonance imaging systems. In this work, gadolinium-doped HA nanorods were synthesized aiming the use as theranostic system for osteosarcomas. The as-prepared HA-Gd nanorods were characterized by XRD with Rietveld refinement method, FTIR, XPS, ICP-AES, TEM, SEM, BET and VSM in order to investigate the physical-chemical, morphology, pore size distribution and magnetic properties. Moreover, phosphorous and gadolinium in the HA-Gd sample were activated by neutron capture, in a nuclear reactor, producing "3"2P and "1"5"9Gd radioisotopes, and the surfaces of these nanorods were functionalized with folic acid. The results indicate that Gd"3"+ are trapped in the HA nanorods crystal net showing great stability of the HA-Gd interaction. Gadolinium provide paramagnetic properties on HA nanorods and structural phosphorous and gadolinium can be activated to induced gamma and beta activity. The well succeeded production of "1"5"9Gd-"3"2P-HA makes this material a promisor agent to act as a theranostic system. - Highlights: • Gd- HA nanorods were synthesized aiming their use as theranostic system. • Gd"3"+ ions are trapped in the HA nanorods crystal net showing great stability. • Gd- HA presents paramagnetic behavior indicating their use as contrast agents. • HA-"1"5"9Gd-"3"2P were successful produced by neutron activation to act as a theranostic system.

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