28 research outputs found
Temperature Dependence of Spin Density in NiAl: Comparison with Pure Ni
No full textThe results of a spin density measurement in the compound NiAl as functions of both temperature and magnetic field are reported. A comparative analysis of the present data with those measured in both NiAl at 4.2 K (Felcher G.P. et al., Phys. Rev. B16 (1977) 2124) and pure Ni at various temperatures (Brown P.J. et al., J. Phys. I France 1 (1991) 1529) is presented. By means of this analysis, the deformation of the electron distribution is deduced and the connection with the formation of a magnetic phase in Ni-based systems is enhanced
Structure magnétique des composés RIr2 — Terres rares — Iridium
No full textNeutron diffraction measurements on the cubic ferromagnetic Laves phases Tb Ir2 and Ho Ir2 confirm the low molecular moments deduced from magnetic measurements. Partial quenching of the orbital angular momentum of the rare-earth atoms is indicated. The coherent scattering amplitude of Ir was determined to be (1,00 ± 0,02) × 10^-12 cm.Des mesures par diffraction neutronique des phases ferromagnétiques et cubiques de Laves Tb Ir2 et Ho Ir2 confirment les faibles moments moléculaires déduits de mesures magnétiques. Un blocage partiel du moment orbital angulaire des atomes de terre rare est probable. L'amplitude de diffusion cohérente de Ir a été déterminée. Elle est de (1,00 ± 0,02) × 10^-12 cm
The fragile magnetic structures of Fe/CeH2−δ multilayers
No full textFe/CeH2-delta multilayers exhibit at room temperature evidence of interlayer exchange coupling. Subsequent Fe layers are either parallel or antiparallel to each other, depending on the Fe and CeH2-delta layer thickness. However, when both layers have thickness larger than similar to 15 Angstrom, the antiferromagnetic structure becomes fragmented into domains laterally limited to a few microns, and the magnetic structures become very fragile. Small magnetic fields of a few Oersteds acting on the samples during growth induce helimagnetic configurations which coexist with antiferromagnetic coupling. The magnetic structures can be permanently destroyed by applying magnetic fields larger than 150 Oe. (C) 2000 Elsevier Science B.V. All rights reserved
Retrieval of phase information in neutron reflectometry
No full textNeutron reflectometry can determine unambiguously the chemical depth profile of a thin film if both phase and amplitude of the reflectance are known. The recovery of the phase information is achieved by adding to the unknown layered structure a known ferromagnetic layer. The ferromagnetic layer is magnetized by an external magnetic field in a direction lying in the plane of the layer and subsequently perpendicular to it. The neutrons are polarized either parallel or opposite to the magnetic field. In this way three measurements can be made, with different (and known) scattering-length densities of the ferromagnetic layer. The reflectivity obtained from each measurement can be represented by a circle in the (complex) reflectance plane. The intersections of these circles provide the reflectance
On the Scale of Diffusion Lengths Observable by Neutron Reflection: Application to Polymers.
No full textABSTRACTA systematic approach has been applied to neutron reflectivity data to study interdiffusion across an interface. It is shown that with this technique it is possible to probe interface broadening from ∼10Å to upward of 200 Å, the upper limit being already within the range of observation of other techniques such as Rutherford backscattering spectrometry (RBS), forward recoil spectrometry (FRES) and secondary ions massspectroscopy (SIMS). As example is analyzed the interdiffusion of a bilayered polymer system: a deuterated polystyrene (d-PS) layer on protonated polystyrene (h-PS).</jats:p
