3,311 research outputs found
Optical Properties of Crystals with Spatial Dispersion: Josephson Plasma Resonance in Layered Superconductors
We derive the transmission coefficient, , for grazing incidence of
crystals with spatial dispersion accounting for the excitation of multiple
modes with different wave vectors for a given frequency . The
generalization of the Fresnel formulas contains the refraction indices of these
modes as determined by the dielectric function . Near
frequencies , where the group velocity vanishes, depends
also on an additional parameter determined by the crystal microstructure. The
transmission is significantly suppressed, if one of the excited modes is
decaying into the crystal. We derive these features microscopically for the
Josephson plasma resonance in layered superconductors.Comment: 4 pages, 2 figures, epl.cls style file, minor change
Field Dependence of the Josephson Plasma Resonance in Layered Superconductors with Alternating Junctions
The Josephson plasma resonance in layered superconductors with alternating
critical current densities is investigated in a low perpendicular magnetic
field. In the vortex solid phase the current densities and the squared bare
plasma frequencies decrease linearly with the magnetic field. Taking into
account the coupling due to charge fluctuations on the layers, we extract from
recent optical data for SmLa_{1-x} Sr_x CuO_{4-delta} the Josephson penetration
length lambda_{ab} approximately 1100 A parallel to the layers at T=10 K.Comment: 5 pages, 6 eps-figures, final version with minor misprints correcte
Effect of remobinant granulocyte-macrophage colony stimulating factor (GM-CSF) on leukopenia in AIDS
Magnetic Mn5Ge3 nanocrystals embedded in crystalline Ge: a magnet/semiconductor hybrid synthesized by ion implantation
The integration of ferromagnetic Mn5Ge3 with the Ge matrix is promising for
spin injection in a silicon-compatible geometry. In this paper, we report the
preparation of magnetic Mn5Ge3 nanocrystals embedded inside the Ge matrix by Mn
ions implantation at elevated temperature. By X-ray diffraction and
transmission electron microscopy, we observe crystalline Mn5Ge3 with variable
size depending on the Mn ion fluence. The electronic structure of Mn in Mn5Ge3
nanocrystals is 3d6 configuration, the same as in bulk Mn5Ge3. A large positive
magnetoresistance has been observed at low temperatures. It can be explained by
the conductivity inhomogeneity in the magnetic/semiconductor hybrid system.Comment: 16 pages, 5 figure
Teste de estabilidade de corante natural da casca de jabuticaba (Myrciaria sp.) em extrato hidrossolúvel de soja comercial.
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