M. Tsunekawa

Kondo Lattice Effects of YbAl3 Suggested by Temperature Dependence of High-Accuracy High-Energy Photoelectron Spectroscopy

By use of high-resolution soft X-rays, intrinsic temperature dependences of bulk Yb 4f photoelectron spectra were obtained for fractured surfaces of high-purity YbAl 3 single crystals. The spectra ...

Technique for bulk Fermiology by photoemission applied to layered ruthenates

We report the Fermi surfaces of the superconductor

Low-Energy Electronic Structure of the Kondo Insulator YbB12

{\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}

Low-Energy Electronic Structure of the Kondo Insulator YbB{sub {bold 12}}

and the nonsuperconductor

Temperature-dependent change of correlated electronic states in Yb4As3 and Yb4(As1-xSbx)3 probed by high resolution photoemission spectroscopy

{\mathrm{Sr}}_{1.8}{\mathrm{Ca}}_{0.2}{\mathrm{RuO}}_{4}

Photoemission Spectroscopy of Sm4As3 Using Soft and Hard X-rays

probed by bulk-sensitive high-energy angle-resolved photoemission. It is found that there is one square-shaped hole-like, one square-shaped electron-like, and one circle-shaped electron-like Fermi surface in both compounds. These results provide direct evidence for nesting instability giving rise to magnetic fluctuations. Our study clarifies that the electron correlation effects are changed with composition depending on the individual band.

Intrinsic correlated electronic structure of CrO2 revealed by hard x-ray photoemission spectroscopy

We have studied the low-energy electronic structure of a Kondo insulator YbB{sub 12} by high-resolution photoemission spectroscopy. A {open_quote}{open_quote}Kondo peak{close_quote}{close_quote} is observed {approximately}25 meV below the Fermi level, which agrees well with the Kondo temperature, whereas the gap at the Fermi level is found much smaller, indicating that the magnetic properties at higher temperatures (75 K) are indeed determined by the Kondo effect in spite of the gap formation at lower temperatures. A renormalized band picture is presented to describe the coexistence of the Kondo peak and the transport gap as well as the highly asymmetric line shape of the Kondo peak. {copyright} {ital 1996 The American Physical Society.}

High resolution photoemission study of CeRu2Si2

We have studied the low-energy electronic structure of a Kondo insulator YbB{sub 12} by high-resolution photoemission spectroscopy. A {open_quote}{open_quote}Kondo peak{close_quote}{close_quote} is observed {approximately}25 meV below the Fermi level, which agrees well with the Kondo temperature, whereas the gap at the Fermi level is found much smaller, indicating that the magnetic properties at higher temperatures (75 K) are indeed determined by the Kondo effect in spite of the gap formation at lower temperatures. A renormalized band picture is presented to describe the coexistence of the Kondo peak and the transport gap as well as the highly asymmetric line shape of the Kondo peak. {copyright} {ital 1996 The American Physical Society.}

Bulk-Sensitive Photoemission Spectroscopy for Heavy-Fermion Pr Compounds Using Hard X-Ray

Clear changes of the Yb 4f photoemission spectra with temperature are observed in Yb 4 As 3 by high resolution photoemission spectroscopy. The photoemission intensity is very low at the Fermi level and decreases as the temperature is lowered in accord with the narrowing of the 4f spectra. Bulk and surface contributions are deconvoluted in the 4f 13 final state spectra. In comparison with the corresponding results in Yb 4 (As 1- x Sb x ) 3 , the spectral changes of Yb 4 As 3 with temperature are confirmed to be beyond simple thermal broadening effects and related to the charge ordering effects. Although the change from the charge ordering temperature ( T t ) down to about T t /2 is consistent with a theoretical prediction, the change below it is rather unusual and may be ascribed to the incompleteness of the charge ordering effect. Spectral changes with Yb 4 Sb 3 -substitution are qualitatively discussed.

Origin of “Hot Spots” in the pseudogap regime of Nd1.85Ce0.15CuO4: An LDA + DMFT + Σk study

The bulk and surface electronic structures of Sm 4 As 3 have been investigated by hard and soft X-ray photoemission spectroscopies (PESs). PES with a wide range of photon energies ( h νs) between 220 and 2450 eV demonstrates the absence of valence mixing in both high- and low-temperature phases, that is, the valence of Sm ions is definitely trivalent in the bulk and divalent on the surface. Atomic multiplet calculations taking into account the bulk and surface spectral weights at each h ν well reproduce the experimental valence band PES and Sm 3 d core-level spectra, supporting the valence difference between bulk and surface in Sm 4 As 3 .