16,705 research outputs found
First-Principles Study of Electronic Structure in -(BEDT-TTF)I at Ambient Pressure and with Uniaxial Strain
Within the framework of the density functional theory, we calculate the
electronic structure of -(BEDT-TTF)I at 8K and room temperature
at ambient pressure and with uniaxial strain along the - and -axes. We
confirm the existence of anisotropic Dirac cone dispersion near the chemical
potential. We also extract the orthogonal tight-binding parameters to analyze
physical properties. An investigation of the electronic structure near the
chemical potential clarifies that effects of uniaxial strain along the a-axis
is different from that along the b-axis. The carrier densities show
dependence at low temperatures, which may explain the experimental findings not
only qualitatively but also quantitatively.Comment: 10 pages, 7 figure
Epitaxial growth and the magnetic properties of orthorhombic YTiO3 thin films
High-quality YTiO3 thin films were grown on LaAlO3 (110) substrates at low
oxygen pressures (<10-8 Torr) using pulsed laser deposition. The in-plane
asymmetric atomic arrangements at the substrate surface allowed us to grow
epitaxial YTiO3 thin films, which have an orthorhombic crystal structure with
quite different a- and b-axes lattice constants. The YTiO3 film exhibited a
clear ferromagnetic transition at 30 K with a saturation magnetization of about
0.7 uB/Ti. The magnetic easy axis was found to be along the [1-10] direction of
the substrate, which differs from the single crystal easy axis direction, i.e.,
[001].Comment: 14 pages, 4 figure
Development of ballast water treatment technology by mechanochemical cavitations
In order to solve environmental problems caused by ballast water, which is a serious problem worldwide, ballast water purification using cavitation was investigated. Previously, only the collapse pressure of cavitation was used for the treatment of planktons. In this study, however, processing by cavitation containing a chemical and the mechanical processing of cavitation were applied. A Venturi nozzle and an ejector nozzle were used to inject sodium hypochlorite. It was found that the ejector nozzle had higher processing performance than the Venturi nozzle, and was effective for high flow rates of ballast water. It was clarified that high plankton extinction ratios could be obtained using mechanochemical cavitation provided by ejector nozzles.http://deepblue.lib.umich.edu/bitstream/2027.42/84238/1/CAV2009-final37.pd
Incommensurate Mott Insulator in One-Dimensional Electron Systems close to Quarter Filling
A possibility of a metal-insulator transition in molecular conductors has
been studied for systems composed of donor molecules and fully ionized anions
with an incommensurate ratio close to 2:1 based on a one-dimensional extended
Hubbard model, where the donor carriers are slightly deviated from quarter
filling and under an incommensurate periodic potential from the anions. By use
of the renormalization group method, interplay between commensurability energy
on the donor lattice and that from the anion potential has been studied and it
has been found that an "incommensurate Mott insulator" can be generated. This
theoretical finding will explain the metal-insulator transition observed in
(MDT-TS)(AuI).Comment: 4 pages, 4 figures, submitted to J. Phys. Soc. Jpn. at December 24
200
Charge ordering in theta-(BEDT-TTF)_2 X materials
We investigate theoretically charge ordered states on the anisotropic
triangular lattice characteristic of the theta-(BEDT-TTF)_2 X materials. Using
exact diagonalization studies, we establish that the charge order (CO) pattern
corresponds to a ``horizontal'' stripe structure, with ...1100... CO along the
two directions with larger electron hopping (p-directions), and ...1010... CO
along the third direction (c-direction). The CO is accompanied by co-operative
bond dimerizations along all three directions in the highest spin state. In the
lowest spin state bonds along the p-directions are tetramerized. Our theory
explains the occurence of a charge-induced high temperature transition as well
as a spin gap transition at lower temperature.Comment: 4 pages, 4 eps figures, uses jpsj2.cl
Pressure effects on the heavy-fermion antiferromagnet CeAuSb2
The f-electron compound CeAuSb2, which crystallizes in the ZrCuSi2-type
tetragonal structure, orders antiferromagnetically between 5 and 6.8 K, where
the antiferromagnetic transition temperature T_N depends on the occupancy of
the Au site. Here we report the electrical resistivity and heat capacity of a
high-quality crystal CeAuSb2 with T_N of 6.8 K, the highest for this compound.
The magnetic transition temperature is initially suppressed with pressure, but
is intercepted by a new magnetic state above 2.1 GPa. The new phase shows a
dome shape with pressure and coexists with another phase at pressures higher
than 4.7 GPa. The electrical resistivity shows a T^2 Fermi liquids behavior in
the complex magnetic state, and the residual resistivity and the T^2
resistivity coefficient increases with pressure, suggesting the possibility of
a magnetic quantum critical point at a higher pressure.Comment: 5 pages, 5 firure
- …