661 research outputs found
Role of electron-electron and electron-phonon interaction effect in the optical conductivity of VO2
We have investigated the charge dynamics of VO2 by optical reflectivity
measurements. Optical conductivity clearly shows a metal-insulator transition.
In the metallic phase, a broad Drude-like structure is observed. On the other
hand, in the insulating phase, a broad peak structure around 1.3 eV is
observed. It is found that this broad structure observed in the insulating
phase shows a temperature dependence. We attribute this to the electron-phonon
interaction as in the photoemission spectra.Comment: 6 pages, 8 figures, accepted for publication in Phys. Rev.
Thermal relaxation in perpendicular double-layered media
科研費報告書収録論文(課題番号:09355012・基盤研究(A)(2)・H9~H11/研究代表者:中村, 慶久/垂直ハード磁気ディスク装置を用いる超大容量ストレージシステムの研究
Characterization of Films with Thickness Less than 10 nm by Sensitivity-Enhanced Atomic Force Acoustic Microscopy
We present a method for characterizing ultrathin films using sensitivity-enhanced atomic force acoustic microscopy, where a concentrated-mass cantilever having a flat tip was used as a sensitive oscillator. Evaluation was aimed at 6-nm-thick and 10-nm-thick diamond-like carbon (DLC) films deposited, using different methods, on a hard disk for the effective Young's modulus defined as E/(1 - ν2), where E is the Young's modulus, and ν is the Poisson's ratio. The resonant frequency of the cantilever was affected not only by the film's elasticity but also by the substrate even at an indentation depth of about 0.6 nm. The substrate effect was removed by employing a theoretical formula on the indentation of a layered half-space, together with a hard disk without DLC coating. The moduli of the 6-nm-thick and 10-nm-thick DLC films were 392 and 345 GPa, respectively. The error analysis showed the standard deviation less than 5% in the moduli
Potencial de fornecimento de nitrogênio (15N) de adubos verdes e mineral para o arroz irrigado.
bitstream/CPACT/9846/1/boletim_21.pd
Photoemission evidence for a Mott-Hubbard metal-insulator transition in VO
The temperature () dependent metal-insulator transition (MIT) in VO is
investigated using bulk sensitive hard x-ray ( 8 keV) valence band, core
level, and V 2 resonant photoemission spectroscopy (PES). The valence
band and core level spectra are compared with full-multiplet cluster model
calculations including a coherent screening channel. Across the MIT, V 3
spectral weight transfer from the coherent ( final)
states at Fermi level to the incoherent ( final)
states, corresponding to the lower Hubbard band, lead to gap-formation. The
spectral shape changes in V 1 and V 2 core levels as well as the valence
band are nicely reproduced from a cluster model calculations, providing
electronic structure parameters. Resonant-PES finds that the
states resonate across the V 2 threshold in
addition to the and states. The results support
a Mott-Hubbard transition picture for the first order MIT in VO.Comment: 6 pages, 3 figures. to be published in Phys. Rev.
Preparation and characterization of epitaxial Fe2-xTixO3 films with various Ti concentrations (0.5 < x < 1.0)
An ilmenite-hematite solid solution ( Fe2-xTixO3 ) is one of the candidates for practical magnetic
semiconductors with a high Curie temperature. We have prepared well-crystallized epitaxial
Fe2-xTixO3 films with a wide range of Ti concentrations - x=0.50, 0.60, 0.65, 0.76, 0.87, and
0.94 - on α-Al2O3(001) substrates. The films are prepared by a reactive helicon plasma sputtering
technique to evaporate Fe and TiO targets simultaneously under optimized oxygen pressure
conditions. The structural characterizations of the films reveal that all films have a single phase of
the ordered structure with R3 symmetry, where Ti-rich and Fe-rich layers are stacked alternately
along the c axis. All films have large ferrimagnetic moments at low temperature, and room
temperature magnetization is clearly observed at x<0.7. The inverse temperature dependence of the
resistivities of the films indicates their semiconducting behavior. The film resistivities decrease with
decreasing Ti concentration.</p
Spiral inflow feeding the nuclear starburst in M83, observed in H-alpha emission with the GHAFAS Fabry-Perot interferometer
We present observations of the nearby barred starburst galaxy, M83 (NGC5236),
with the new Fabry-Perot interferometer GHAFAS mounted on the 4.2 meter William
Herschel Telescope on La Palma. The unprecedented high resolution observations,
of 16 pc/FWHM, of the H-alpha-emitting gas cover the central two kpc of the
galaxy. The velocity field displays the dominant disk rotation with signatures
of gas inflow from kpc scales down to the nuclear regions. At the inner Inner
Lindblad Resonance radius of the main bar and centerd at the dynamical center
of the main galaxy disk, a nuclear rapidly
rotating disk with scale length of pc has formed. The nuclear
starburst is found in the vicinity as well as inside this nuclear disk, and our
observations confirm that gas spirals in from the outer parts to feed the
nuclear starburst, giving rise to several star formation events at different
epochs, within the central 100 pc radius of M83.Comment: Accepted for publication in ApJ Letters. High-resolution version can
be found at http://www.astro.su.se/~kambiz/DOC/paper-M83.pd
Potencial de utilização de leguminosas de inverno como fonte alternativa de nitrogênio para a cultura do arroz irrigado.
bitstream/item/31603/1/comunicado81.pd
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