361 research outputs found
Electronic structures of CeRu ( = Si, Ge) in the paramagnetic phase studied by soft X-ray ARPES and hard X-ray photoelectron spectroscopy
Soft and hard X-ray photoelectron spectroscopy (PES) has been performed for
one of the heavy fermion system CeRuSi and a -localized ferromagnet
CeRuGe in the paramagnetic phase. The three-dimensional band structures
and Fermi surface (FS) shapes of CeRuSi have been determined by soft
X-ray -dependent angle resolved photoelectron spectroscopy (ARPES). The
differences in the Fermi surface topology and the non- electronic
structures between CeRuSi and CeRuGe are qualitatively
explained by the band-structure calculation for both itinerant and
localized models, respectively. The Ce valences in CeRu ( = Si, Ge)
at 20 K are quantitatively estimated by the single impurity Anderson model
calculation, where the Ce 3d hard X-ray core-level PES and Ce 3d X-ray
absorption spectra have shown stronger hybridization and signature for the
partial contribution to the conduction electrons in CeRuSi.Comment: 8figure
Data assimilation of CALIPSO aerosol observations
We have developed an advanced data assimilation system for a global aerosol model with a four-dimensional ensemble Kalman filter in which the Level 1B data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were successfully assimilated for the first time, to the best of the authors' knowledge. A one-month data assimilation cycle experiment for dust, sulfate, and sea-salt aerosols was performed in May 2007. The results were validated via two independent observations: 1) the ground-based lidar network in East Asia, managed by the National Institute for Environmental Studies of Japan, and 2) weather reports of aeolian dust events in Japan. Detailed four-dimensional structures of aerosol outflows from source regions over oceans and continents for various particle types and sizes were well reproduced. The intensity of dust emission at each grid point was also corrected by this data assimilation system. These results are valuable for the comprehensive analysis of aerosol behavior as well as aerosol forecasting
Direct experimental verification of applicability of single-site model for angle integrated photoemission of small concentrated Ce compounds
Bulk-sensitive high-resolution Ce 4f spectra have been obtained from 3d
4f resonance photoemission measurements on LaCeAl and
LaCeRu for . The 4f spectra of
low-Kondo-temperature () (La,Ce)Al are essentially identical except
for a slight increase of the Kondo peak with , which is consistent with a
known increase of with . In contrast, the 4f spectra of high-
(La,Ce)Ru show a Kondo-like peak and also a 0.5 eV structure which
increases strongly with . The resonance photon-energy dependences of the two
contributions are different and the origin of the 0.5 eV structure is still
uncertain.Comment: submitted to SCES 2001, two-columnn format, modified tex
Electron correlation in FeSe superconductor studied by bulk-sensitive photoemission spectroscopy
We have investigated the electronic structures of recently discovered
superconductor FeSe by soft-x-ray and hard-x-ray photoemission spectroscopy
with high bulk sensitivity. The large Fe 3d spectral weight is located in the
vicinity of the Fermi level (EF), which is demonstrated to be a coherent
quasi-particle peak. Compared with the results of the band structure
calculation with local-density approximation, Fe 3d band narrowing and the
energy shift of the band toward EF are found, suggesting an importance of the
electron correlation effect in FeSe. The self energy correction provides the
larger mass enhancement value (Z^-1=3.6) than in Fe-As superconductors and
enables us to separate a incoherent part from the spectrum. These features are
quite consistent with the results of recent dynamical mean-field calculations,
in which the incoherent part is attributed to the lower Hubbard band.Comment: 8 pages, 5 figures, 1 talbl
Possible Kondo resonance in PrFe4P12 studied by bulk-sensitive photoemission
Pr 4f electronic states in Pr-based filled skutterudites PrT4X12(T=Fe and Ru;
X=P and Sb) have been studied by high-resolution bulk-sensitive Pr 3d-4f
resonance photoemission. A very strong spectral intensity is observed just
below the Fermi level in the heavy-fermion system PrFe4P12. The increase of its
intensity at lower temperatures is observed. We speculate that this is the
Kondo resonance of Pr, the origin of which is attributed to the strong
hybridization between the Pr 4f and the conduction electrons.Comment: 4 pages(camera ready format), 4 figures, ReVTeX
Bulk-sensitive Photoemission of Mn5Si3
We have carried out a bulk-sensitive high-resolution photoemission experiment
on Mn5Si3. The measurements are performed for both core level and valence band
states. The Mn core level spectra are deconvoluted into two components
corresponding to different crystallographic sites. The asymmetry of each
component is of noticeable magnitude. In contrast, the Si 2p spectrum shows a
simple Lorentzian shape with low asymmetry. The peaks of the valence band
spectrum correspond well to the peak positions predicted by the former band
calculation.Comment: To be published in: Solid State Communication
High-resolution Ce 3d-edge resonant photoemission study of CeNi_2
Resonant photoemission (RPES) at the Ce 3d -> 4f threshold has been performed
for alpha-like compound CeNi_2 with extremely high energy resolution (full
width at half maximum < 0.2 eV) to obtain bulk-sensitive 4f spectral weight.
The on-resonance spectrum shows a sharp resolution-limited peak near the Fermi
energy which can be assigned to the tail of the Kondo resonance. However, the
spin-orbit side band around 0.3 eV binding energy corresponding to the f_{7/2}
peak is washed out, in contrast to the RPES spectrum at the Ce 3d -> 4f RPES
threshold. This is interpreted as due to the different surface sensitivity, and
the bulk-sensitive Ce 3d -> 4f RPES spectra are found to be consistent with
other electron spectroscopy and low energy properties for alpha-like
Ce-transition metal compounds, thus resolves controversy on the interpretation
of Ce compound photoemission. The 4f spectral weight over the whole valence
band can also be fitted fairly well with the Gunnarsson-Schoenhammer
calculation of the single impurity Anderson model, although the detailed
features show some dependence on the hybridization band shape and (possibly) Ce
5d emissions.Comment: 4 pages, 3 figur
- …