[en] The need for not only bulk sensitive but also extremely high resolution photoelectron spectroscopy for studying detailed electronic structures of strongly correlated electron systems is growing rapidly. Moreover, easy access to such a capability in one's own laboratory is desirable. Demonstrated here is the performance of a microwave excited rare gas (Xe, Kr, and Ar) lamp combined with ionic crystal filters (sapphire, CaF₂, and LiF), which can supply three strong lines near the photon energy of hnyu hν=8.4, 10.0, and 11.6 eV, with the hν resolution of better than 600 μeV for photoelectron spectroscopy. Its performance is demonstrated on some materials by means of both angle-integrated and angle-resolved measurements.

[en] Dependence of the spectral functions near the Fermi level on temperature and rare-earth atom doping was studied in detail for strongly correlated alloys Sm_1−xEu_xB₆ and Yb_1−xLu_xB₁₂ by photoelectron spectroscopy at ∼8000 eV as well as at 7 and 8.4 eV. It was found that the 4f lattice coherence and intrinsic gap are robust for Sm_1−xEu_xB₆ at least up to the Eu substitution of x = 0.15 while both collapse by Lu substitution already at x = 0.125 for Yb_1−xLu_xB₁₂. As for the temperature dependence of the spectral shapes near the Fermi level at low temperatures, rather contrasting results were observed between YbB₁₂ and SmB₆. Although the gap shape does not change below 15 K for YbB₁₂ with the characteristic temperature T* of 80 K, the spectral shape of SmB₆ with a T* of 140 K shows that the peak beyond the gap is further increased below 15 K. The temperature dependence of the spectra near the intrinsic gap is clearly different between SmB₆ and YbB₁₂, although both materials have so far been categorized in the same kind of strongly correlated semiconductor. The possibility of the surface contribution is discussed for SmB₆. (paper)

[en] X-ray photoemission spectra of Mn_1-xCr _xAu₂ (x = 0, 0.05, and 0.13) are presented and compared with theoretical total and partial density of state (DOS) curves. Site- and spin-decomposed partial DOS and magnetism of these materials are also discussed