Visible photoluminescence (PL) can be observed in a-SiOx and a-SiOx:H alloys prepared by evaporation of SiO in ultrahigh vacuum and under a flow of hydrogen ions, respectively. The hydrogen and oxygen bonding is studied by infrared spectrometry. The hydrogen stability is followed by thermal desorption spectrometry experiments. The evolution of the PL with annealing treatments shows that the PL can be attributed to a quantum confinement effect in a-Si clusters embedded in the matrix of a-SiOx. Hydrogen does not greatly contribute to the PL efficiency and to the thermal evolution of the a-Si clusters.
By following the experimental results recently published about electronic-energy-deposition-induced effects in metallic materials, a mixing effect is observed in an Fe/Si multilayer irradiated by 650 MeV uranium ions. Mössbauer spectroscopy shows that, after a fluence as low as 1013 cm-2, an Fe 4.5 nm/Si 3.5 nm multilayer has been made almost homogeneous by ion mixing. On electron micrographs, at very low fluence, latent tracks are observed where the magnetic properties are drastically modified from the previous crystalline ferromagnetic state.
We present a magnetization and neutron-diffraction study of the basal plane magnetic structure of Dy epitaxial films and Dy/Er superlattices. The thermal evolution of the magnetic phases, the stability of the helical phase under a magnetic field, the thermal variation of the dysprosium in-plane and c parameters, and of the dysprosium turn angle are successively shown. In Dy/Er superlattices, the dysprosium helix propagates coherently through paramagnetic erbium; at low temperature, individual dysprosium layers undergo a ferromagnetic transition and are coupled antiferromagnetically to each other for erbium layers thicknesses larger than 20 Å. In dysprosium films, as expected from the epitaxy effect, the Curie temperature of dysprosium is reduced if dysprosium is grown on yttrium and increased if it is grown on erbium, whereas it is unexpectedly close to the bulk value in Dy/Er superlattices. This amazing value of the Curie temperature in superlattices is correlated to two main experimentally observed effects: ͑i͒ the magnetoelastic driving force is reduced compared to bulk dysprosium because of the clamped ␥ distortion; ͑ii͒ the difference between the exchange energies in the helical and the ferromagnetic phases is increased compared to the bulk value.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.