59 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
Prominent 5d-orbital contribution to the conduction electrons in gold
We have examined the valence-band electronic structures of gold and silver in
the same column in the periodic table with nominally filled d orbitals by means
of a recently developed polarization-dependent hard x-ray photoemission.
Contrary to a common expectation, it is found that the 5d-orbital electrons
contribute prominently to the conduction electrons in gold while the conduction
electrons in silver are to some extent free-electron-like with negligible 4d
contribution, which could be related to a well-known fact that gold is more
stable than silver in air. The 4d electron correlation effects are found to be
essential for the conduction electron character in silver.Comment: 8 pages, 4 figures, to be appeared in New J. Phys
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
Charge dynamics in strongly correlated one-dimensional Cu-O chain systems revealed by inelastic X-ray scattering
We report on the Cu 1s resonant inelastic X-ray scattering (RIXS) of Cu-O
one-dimensional (1D) strongly correlated insulator systems with contrasting
atomic arrangements, namely edge-sharing CuGeO3 and corner-sharing Sr2CuO3.
Owing to good statistics of the high-resolution RIXS data, so far unresolved
fine structures are revealed. Detailed photon-energy and momentum dependence of
the RIXS spectra in comparison with theoretical calculations has clarified the
natures of the low-energy charge excitations and hybridization of the
electronic states.Comment: 4 pages, 3 color figure
Impact of the ground-state symmetry for anisotropic -hybridization in the heavy fermion superconductor CeNiGe
We report the ground-state symmetry of the Ce states in the heavy
fermion superconductor CeNiGe, yielding anisotropic
-hybridization between the Ce states and conducting electrons. By
analyzing linear dichroism in soft x-ray absorption and core-level hard x-ray
photoemission spectra, the symmetry is determined as -type
, promoting predominant hybridization with the conducting electrons
originating from the Ge site. The band structures probed by the soft x-ray
angle-resolved photoemission indicates that the Ge components contribute
to the band renormalization through the anisotropic hybridization effects,
suggesting that the control of the electronic structures of Ge orbital gives an
impact to achieve the exotic phenomena in CeNiGe
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