The role of chemical structure on the magnetic and electronic properties of Co2FeAl0.5Si0.5/Si(111) interface

We show that Co2FeAl0.5Si0.5 film deposited on Si(111) has a single crystal structure and twin related epitaxial relationship with the substrate. Sub-nanometer electron energy loss spectroscopy shows that in a narrow interface region there is a mutual inter-diffusion dominated by Si and Co. Atomic resolution aberration-corrected scanning transmission electron microscopy reveals that the film has B2 ordering. The film lattice structure is unaltered even at the interface due to the substitu- tional nature of the intermixing. First-principles calculations performed using structural models based on the aberration corrected electron microscopy show that the increased Si incorporation in the film leads to a gradual decrease of the magnetic moment as well as significant spin-polarization reduction. These effects can have significant detrimental role on the spin injection from the Co2FeAl0.5Si0.5 film into the Si substrate, besides the structural integrity of this junction

Magnetic and structural depth profiles of Heusler alloy Co2FeAl0.5Si0.5 epitaxial films on Si(1 1 1)

The depth-resolved chemical structure and magnetic moment of Co2FeAl0.5Si0.5, thin films grown on Si(1 1 1) have been determined using x-ray and polarized neutron reflectometry. Bulk-like magnetization is retained across the majority of the film, but reduced moments are observed within 45˚A of the surface and in a 25˚A substrate-interface region. The reduced moment is related to compositional changes due to oxidation and diffusion, which are further quantified by elemental profiling using electron microscopy with electron energy loss spectroscopy. The accuracy of structural and magnetic depth-profiles obtained from simultaneous modeling is discussed using different approaches with different degree of constraints on the parameters. Our approach illustrates the challenges in fitting reflectometry data from these multi-component quaternary Heusler alloy thin films

Effect of annealing on the structure and magnetic properties of Co2FeAl0.5Si0.5 thin films on Ge(111)

Abstract We present a magnetic and structural properties study of epitaxially grown B2-ordered full Heusler Co2FeSi0.5Al0.5 single crystal films on Ge(111) substrates, as a function of annealing temperature. Hysteresis loop measurements reveal that the magnetic properties of Co2FeSi0.5Al0.5 are stable up to 450 °C while ferromagnetic resonance linewidth measurements show a reduction of Gilbert damping from 5.6 × 10−3 to 2.9 × 10−3 for as-grown and annealed film, respectively. Above 500 °C, the films have increased coercivity, decreased saturation magnetisation, and show characteristic two-magnon scattering resonance line-shapes. Magnetic inhomogeneities developed within the film when annealed above 500 °C were correlated to significant interdiffusion at the film-substrate interface, as confirmed by scanning transmission electron microscopy and electron energy loss spectroscopy. By performing first-principles calculations based on atomistic models developed from atomically-resolved microscopy images, we show the magnetic moment of the Co2FeSi0.5Al0.5 film reduces upon Co substitution by Ge atoms

3,8-diazabicyclo[3.2.1]octane derivatives as analogues of abasilide, a class III antiarrhythmic agent

La structure de la biodiversité du milieu profond et ses déterminants ainsi que les effets des perturbations naturelles ou anthropologiques restent globalement mal connus (McClain et Schlacher, 2015). Les monts sous-marins, principale cible potentielle de l’exploitation minière en Polynésie française, sont néanmoins reconnus comme fournissant une grande variété de services écosystémiques (Armstrong et al., 2012, Rossi, 2013) notamment en termes de ressources halieutiques (Morato et al., 2010)..

A review of polycyclic aromatic hydrocarbons and their substitutions in full‐scale wastewater treatment plants

Wastewater treatment plants (WWTPs) become a main contributor of polycyclic aromatic hydrocarbons (PAHs) and their substitutions present in freshwater systems. This paper reviews PAHs and their substitutions in full-scale WWTPs including their fate and behaviors, analytical techniques, biological treatments, feasibility examination, and modeling. In addition, challenges and future outlook are also highlighted. This study found that PAHs and their substitutions have been detected in WWTPs. GC-MS and HPLC analytical methods have been found to be acceptable for the detection and analysis of PAHs and their substitutions. Although some biological treatments such as activated sludge and membrane bioreactors are capable for the treatment process, their technical, social, economic, and environmental aspects must be considered. The fate and treatability estimator (FATE) model has been used for the modeling of removal of PAHs in full-scale WWTPs, but in some cases their shortcoming has been reported, which calls for an evaluation and modification of the model based on physicochemical processes