632 research outputs found
Polarized Neutron Inelastic Scattering Study of the Anisotropic Magnetic Fluctuations in the Quasi-1D Ising-like Antiferromagnet TlCoCl
Polarized neutron inelastic scattering experiments have been carried out in
the quasi-1D Ising-like antiferromagnet TlCoCl. We observed the
longitudinal magnetic fluctuation for the spin-wave
excitation continuum, which has not been observed in the unpolarized neutron
inelastic scattering experiments of the quasi-1D Ising-like antiferromagnets
CsCoCl and TlCoCl so far, together with the transverse magnetic
fluctuation . We compared both obtained intensities of
and with the perturbation theory from
the pure Ising limit by Ishimura and Shiba, and a semi-quantitative agreement
was found.Comment: 5 pages, 5 figures, jpsj2.cls, to be published in J. Phys. Soc. Jpn.
Vol. 75 (2006) No.
Sulfur-Mediated Palladium Catalyst Immobilized on a GaAs Surface
We present a hard x-ray photoelectron spectroscopy study on the preparation process of palladium catalyst immobilized on an S-terminated GaAs(100) surface. It is revealed that Pd(II) species are reduced on the GaAssurface and yield Pd nanoparticles during the process of Pd immobilization and the subsequent heat treatment. A comparison with the results on GaAs without S-termination suggests that the reduction of Pd is promoted by hydroxy groups during the Pd immobilization and by S during the heat treatment
Topology optimization for flextensional actuators
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76744/1/AIAA-1998-4951-939.pd
Magnetic Excitations in the Quasi-1D Ising-like Antiferromagnet TlCoCl
Neutron inelastic scattering measurements have been performed in order to
investigate the magnetic excitations in the quasi-1D Ising-like antiferromagnet
TlCoCl. We observed the magnetic excitation, which corresponds to the
spin-wave excitation continuum corresponding to the domain-wall pair excitation
in the 1D Ising-like antiferromagnet. According to the Ishimura-Shiba theory,
we analyzed the observed spin-wave excitation, and the exchange constant
and the anistropy were estimated as 14.7 meV and 0.14 in TlCoCl,
respectively.Comment: 2 pages, 3 figures, jpsj2.cls, to be published in J. Phys. Soc. Jpn.
Vol.75 (2006) No.
Mechanism of Anomalous Tunneling in Condensed Bose System
We clarify the origin of anomalous tunneling [Yu. Kagan et al. Phys. Rev.
Lett. 90 (2003) 130402] i.e. the perfect transmission at low energy limit of
tunneling of phonon excitations across the potential barrier separating two
Bose condensates. The perfect transmission is a consequence of the coincidence
of the wave function of the excited state at low energy limit and the
macroscopic wave function of the condensate. We show that the perfect
transmission at low energy occurs even at finite temperatures within the scheme
of Popov approximation.Comment: 4 pages 1 figur
Flat Dielectric Grating Reflectors with High Focusing Power
Sub-wavelength dielectric gratings (SWG) have emerged recently as a promising
alternative to distributed-Bragg-reflection (DBR) dielectric stacks for
broadband, high-reflectivity filtering applications. A SWG structure composed
of a single dielectric layer with the appropriate patterning can sometimes
perform as well as thirty or forty dielectric DBR layers, while providing new
functionalities such as polarization control and near-field amplification. In
this paper, we introduce a remarkable property of grating mirrors that cannot
be realized by their DBR counterpart: we show that a non-periodic patterning of
the grating surface can give full control over the phase front of reflected
light while maintaining a high reflectivity. This new feature of dielectric
gratings could have a substantial impact on a number of applications that
depend on low-cost, compact optical components, from laser cavities to CD/DVD
read/write heads.Comment: submitted to Nature Photonic
Unitarity in Dirichlet Higgs Model
We show that a five dimensional Universal Extra Dimension model, compactified
on a line segment, is consistently formulated even when the gauge symmetry is
broken solely by non-zero Dirichlet boundary conditions on a bulk Higgs field,
without any quartic interaction. We find that the longitudinal W+W- elastic
scattering amplitude, under the absence of the Higgs zero-mode, is unitarized
by exchange of infinite towers of KK Higgs bosons. Resultant amplitude scales
linearly with the scattering energy, exhibiting five dimensional nature. A
tree-level partial-wave unitarity condition is satisfied up to 6.7 (5.7) TeV
for the KK scale 430 (500) GeV, favored by the electroweak data within 90% CL.Comment: 14pages, 2 figures (v1); References added (v2); Trivial error
corrected: u -> t and \cos\theta -> -\cos\theta, references added (v3);
comments added, a reference added, version to appear in Eur. Phys. J. C (v4);
Expressions matched to EPJC style, obsolete affiliation (on leave) has been
removed (v5
Combining optical and electrical studies to unravel the effect of Sb doping on CIGS solar cell
A way to lower the manufacturing cost of Cu(In,Ga)Se2 (CIGS) thin film solar cells is to use flexible polymer substrates instead of glass substrates. Because such substrates require a low temperature during absorber deposition, the efficiency of the cells remains slightly lower (18.7%) compared to CIGS on glass substrates (20.3%). Partial compensation of this efficiency loss might be accomplished by Sb doping of the absorber, which is reported to have a positive effect on the morphology of this layer. In this work the defect structure of Sb doped CIGS solar cells is investigated using optical and electrical spectroscopic techniques. Experiments were performed on cells deposited on soda lime glass substrate, adding a thin Sb layer (8, 12 nm) onto the Mo back contact prior to the CIGS absorber deposition. The results are compared with those for cells without Sb doping using the same process. Fourier-Transform near infrared photocurrent measurements in the 10–300K range demonstrate that the band gap of Sb-doped samples is larger than for undoped samples. Photoluminescence spectra in the 5–100K region provide information on shallow-level defects. Deep-Level Transient Spectroscopy spectra of Sb-doped cells exhibit two features not encountered for non-doped cells: 1) a peak at lower temperature than the N1 signal and 2) incomplete charge carrier freeze-out down to 8 K. While the first result appears to be the fingerprint of an extra non-Ohmic contact in the solar cell structure, the second suggests the introduction of a very shallow acceptor by Sb doping. As a salient feature one can accurately monitor the partial hole freeze-out in the 40-60 K range and determine the signature of the intrinsic defects that provide the p-type conductivity of the CIGS absorber using Admittance Spectroscopy
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