Long range electronic phase separation in CaFe3O5

Electronic phase separation is an important feature of many correlated perovskite compounds but hasn’t been seen in other complex oxides with similar physical behaviour such as magnetite. Hong et al. find phase separation between a magnetite-like charge ordered phase and a charge averaged phase in CaFe3O5

Elucidation of the ATP7B N-Domain Mg2+-ATP Coordination Site and Its Allosteric Regulation

The diagnostic of orphan genetic disease is often a puzzling task as less attention is paid to the elucidation of the pathophysiology of these rare disorders at the molecular level. We present here a multidisciplinary approach using molecular modeling tools and surface plasmonic resonance to study the function of the ATP7B protein, which is impaired in the Wilson disease. Experimentally validated in silico models allow the elucidation in the Nucleotide binding domain (N-domain) of the Mg2+-ATP coordination site and answer to the controversial role of the Mg2+ ion in the nucleotide binding process. The analysis of protein motions revealed a substantial effect on a long flexible loop branched to the N-domain protein core. We demonstrated the capacity of the loop to disrupt the interaction between Mg2+-ATP complex and the N-domain and propose a role for this loop in the allosteric regulation of the nucleotide binding process

An iridium rich layer at the Cretaceous/Tertiary boundary in the Bidart Section (southern France)

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Magnetodielectric Effect in Crystals of the Noncentrosymmetric CaOFeS at Low Temperature

International audienceSingle crystals of the stoichiometric iron calcium oxysulfide CaOFeS have been grown by a solid-state reaction. Structural analysis of CaOFeS at room temperature by combining single-crystal X-ray diffraction data and transmission electron microscopy leads to a stoichiometric hexagonal noncentrosymmetric P63mc layered structure isostructural to CaOZnS. It is built from alternating layers made of FeOS3 tetrahedra sharing sulfur apexes and stacked with Ca2+ planes. All Fe-O bonds are parallel to the stacking axis; this breaks the centrosymmetry, leading to a polar structure. The dielectric measurements reveal the existence of a magnetodielectric effect near 33 K in good agreement with the Neel temperature, as evidenced near 35 K by specific heat measurements reported by a different group. (Figure Presented). © 2015 American Chemical Society

Structural Transition at 360 K in the CaFe 5 O 7 Ferrite: Toward a New Charge Ordering Distribution

International audienceAn efficient synthesis route is proposed to obtain single phase powder ceramic of CaFe5O7. This complex structure can be described as an intergrowth between one CaFe2O4 unit and n = 3 slices of FeO Wüstite-type structure. A detailed structural study has been carried out at room temperature combining transmission electron microscopy (TEM) observations (ED, HREM), scanning transmission electron microscopy (STEM-HAADF), and X-ray diffraction data. The analysis of these data has revealed an unexpected supercell with a monoclinic symmetry. From the hkl conditions deduced from the electron diffraction study and the analysis of X-ray diffraction data by simulated annealing, a structural model considering the centrosymmetric P21/m setting can be proposed. In addition the first magnetic and electrical transport measurements are reported showing a sharp peak in magnetic susceptibility and a strong localization around 360 K, associated to a structural change from monoclinic setting to orthorhombic one

Structural Transition at 360 K in the CaFe 5 O 7 Ferrite: Toward a New Charge Ordering Distribution

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