2p resonance photoemission and Auger features in NiS2 and FeS2

Resonance behaviors of the Ni and Fe 3d, 3p and 3s related satellite photoemission and Auger features are measured for the Ni and Fe 2p core excitation in NiS2 and FeS2. Chronological interpretation is proposed to the Ni and Fe 2p3p3d Auger features. A resonance satellite around the binding energy of 30 eV is identified as due to the plasmon satellite associated with the resonance-enhanced satellite of the 3d state

Spin-integrated and spin-resolved photoemission study of Fe chalcogenides

The electronic structures of the antiferromagnetic semiconductor FeS and ferrimagnetic metals Fe7S8 and Fe7Se8 have been studied by spin-integrated and spin-resolved photoemission spectroscopy and inverse-photoemission spectroscopy. The overall Fe 3d bandwidth in the photoemission spectra is 25-30 % narrower than the density of states (DOS) predicted by first-principles band-structure calculations and is accompanied by an intense tail on the high-binding-energy side, indicating the correlated nature of electrons in the Fe 3d band. Deviation from the band DOS is more significant in Fe7S8 than in Fe7Se8, and in the minority-spin spectra than in the majority-spin spectra. Cluster-model calculation for FeS has shown satellite structures at high binding energies, but the calculated spectral line shape is not in good agreement with experiment compared to the band DOS. By introducing a self-energy correction to the band DOS, we could explain the narrowing of the overall Fe 3d bandwidth and the high-binding-energy tail shape but not for the unusual broadening of the Fe 3d band within ∼ 1 eV of the Fermi level

Temperature-Dependent High-Resolution Photoemission Study of the Kondo Insulator YbB12

We have performed a detailed temperature-dependent photoemission study of the conduction-band states in the Kondo insulator YbB12 using single crystalline samples. Measurements with improved energy resolution have revealed (pseudo)gaps of two energy scales. The size of the narrower gap ~10 meV and its disappearance at high temperatures are consistent with the temperature dependence of the electrical resistivity and the magnetic susceptibility. The larger pseudogap of ~100 meV depends on temperature even at room temperature. We discuss how the characteristics of the Kondo insulator are reflected in the conduction-band photoemission spectra