Phase-transitions in high magnetic-fields

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Evolution of the electronic structure from electron-doped to hole-doped states in the two-dimensional Mott-Hubbard system La1.17-xPbxVS3.17

The filling-controlled metal-insulator transition (MIT) in a two-dimensional Mott-Hubbard system La1.17-xPbxVS3.17 has been studied by photoemission spectroscopy. With Pb substitution x, chemical potential mu abruptly jumps by ~ 0.07 eV between x=0.15 and 0.17, indicating that a charge gap is opened at x ~= 0.16 in agreement with the Mott insulating state of the d2 configuration. When holes or electrons are doped into the Mott insulator of x ~= 0.16, the gap is filled and the photoemission spectral weight at mu, rho(mu), gradually increases in a similar way to the electronic specific heat coefficient, although the spectral weight remains depressed around mu compared to that expected for a normal metal, showing a pseudogap behavior in the metallic samples. The observed behavior of varrho(mu)->0 for x->0.16 is contrasted with the usual picture that the electron effective mass of the Fermi-liquid system is enhanced towards the metal-insulator boundary. With increasing temperature, the gap or the pseudogap is rapidly filled up, and the spectra at T=300 K appears to be almost those of a normal metal. Near the metal-insulator boundary, the spectra around mu are consistent with the formation of a Coulomb gap, suggesting the influence of long-range Coulomb interaction under the structural disorder intrinsic to this system.Comment: 8 pages, 12 figure

Application of nonequilibrium concentration profiles in particle diffusion under the action of a magnetic force (abstract)

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Subband-Landau-level spectroscopy in GaAs-AlxGa1-xAs heterojunctions

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HIGH PRECISION BAND CALCULATION OF Nb3Sn IN THE A-15 CUBIC PHASE

Un nouveau calcul de haute precision a été effectué pour les bandes de Nb3Sn au moyen de la méthode APW ; des corrections au potentiel y sont incluses et à l'intérieur et à l'extérieur de la sphère muffin-tin Les résultats (surface de Fermi, densité d'états, etc..) sont en bon accord avec huit expériences différentes. Nous en concluons que notre modèle est d'une bonne précision.A new precision band calculation has been undertaken for Nb3Sn using the APW method with potential corrections included inside and outside the muffin-tin spheres. The results (Fermi surface, density of states, etc..) show good agreement with eight experiments. It is concluded that the band mode1 is highly accurate