15 research outputs found

    Use of anticoagulants and antiplatelet agents in stable outpatients with coronary artery disease and atrial fibrillation. International CLARIFY registry

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    Electronic and optical properties of K-doped ZnO: Ab initio study

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    International audienceWe present the results of ab initio calculations of K-doped ZnO in the wurtzite structure using a supercell of 32 atoms and density functional theory. A complete analysis of its electronic, optical and magnetic properties is provided. The local spin density approximation (LSDA) has been used to analyze the density of states and to understand the K influence at different concentration values. The material is revealed to become a p-type doped semiconductor. The optical constant or refractive index, the dielectric function, and the absorption coefficient were determined and show a good agreement with available experimental data. Potassium doping leads to an absorption peak at about 380 nm. That peak might improve the absorption characteristics of ZnO for solar cell or optical applications

    Influence of the strong field in enhancing, electronic magnetic and optical properties of Mn-doped MgO

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    International audienceThe local spin density approximation with Hubbard-like coulomb term based on first principles calculations are used to investigate a substitute doping of transition metal Mn in MgO. Under the crystal field theory and according to the intensity of the ligand field, the d(4)-d(8) transition elements can have two possible configurations such as the case of Mn(d(5)), in its low spin configuration that represents a strong field, the Mn+2 doped MgO material has a half-metallic character in the two proposed studies approximations: the local spin density approximation (LSDA) and (LSDA + U), a character that will enable to change the magnetic, electronic and optical properties., This result is supported by the sp-d exchange mechanism calculation confirming that the coupling between impurity and ligand is completely ferromagnetic. The material has a magnetic moment of about 1 mu(B), mainly due to the Mn impurity of around 95% in LSDA + U case. In optical propriety the material shows a slight spin polarization and reduction of band gap of around 5% with strong filed in LSDA + U case. (C) 2017 Elsevier GmbH. All rights reserved

    The manganese effect on the magnetism and optical properties especially interband transitions of zinc sulphide

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    International audienceThe electronic, magnetic and optical properties of Mn doped zinc sulphide (ZnS:Mn) were calculated with the FP-LAPW method by using the LSDA and LSDA+U approximations. The latter one is shown to be necessary to account for the strong electron correlation in the Mn 3d shell. With the increase of Mn2+ concentration, the band gap is decreased for the spin-up channel and increased for the spin-down channel. Furthermore, to calculate the correct exchange couplings d-d and sp-d of Mn-doped ZnS, we have applied the Hubbard U parameter on Mn-d states. The influence of this Hubbard U parameter on the optical, electronic and magnetic properties of ZnS:Mn is investigated. We found that U=6 eV gives good results for exchange couplings and optical properties close to the experimental ones. The magnetic coupling between neighboring Mn impurities in ZnS is found to be antiferromagnetic. (C) 2016 Elsevier B.V. All rights reserved
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