Kondo interactions from band reconstruction in YbInCu

Jarrige, I.*; Kotani, Akio*; Yamaoka, Hitoshi*; Tsujii, Naohito*; Ishii, Kenji; Upton, M.*; Casa, D.*; Kim, J. H.*; Gog, T.*; Hancock, J. N.*

Physical Review Letters, 114(12), p.126401_1 - 126401_5, 2015/03

https://doi.org/10.1103/PhysRevLett.114.126401

Resonant inelastic X-ray scattering study of charge excitations in superconducting and nonsuperconducting PrFeAsO

Jarrige, I.*; Nomura, Takuji; Ishii, Kenji; Gretarsson, H.*; Kim, Y.-J.*; Kim, J.*; Upton, M.*; Casa, D.*; Gog, T.*; Ishikado, Motoyuki*; et al.

Physical Review B, 86(11), p.115104_1 - 115104_4, 2012/09

https://doi.org/10.1103/PhysRevB.86.115104

We report the first observation by momentum-resolved resonant inelastic X-ray scattering of charge excitations in an iron-based superconductor and its parent compound, PrFeAsO and PrFeAsO respectively, with two main results. First, using calculations based on a 16 band model, we show that the energy of the lowest-lying excitations, identified as interband transitions of dominant , orbital character, exhibits a dramatic dependence on electron correlation. This enables us to estimate the Coulomb repulsion and Hund's coupling , and to highlight the role played by in these peculiar orbital-dependent electron correlation effects. Second, we show that short-range antiferromagnetic correlations, which are a prerequisite to the occurrence of these excitations at the point, are still present in the superconducting state.

Incident energy and polarization-dependent resonant inelastic X-ray scattering study of LaCuO

Lu, L.*; Hancock, J. N.*; Chabot-Couture, G.*; Ishii, Kenji; Vajk, O. P.*; Yu, G.*; Mizuki, Junichiro; Casa, D.*; Gog, T.*; Greven, M.*

Physical Review B, 74(22), p.224509_1 - 224509_9, 2006/12

https://doi.org/10.1103/PhysRevB.74.224509

We present a detailed Cu -edge resonant inelastic X-ray scattering (RIXS) study of the Mott insulator LaCuO in the 1-7 eV energy loss range. As initially found for the high-temperature superconductor HgBaCuO, the spectra exhibit a multiplet of weakly dispersive electron-hole excitations, which are revealed by utilizing the subtle dependence of the cross section on the incident photon energy. The close similarity between the fine structures for in-plane and out-of-plane polarizations is indicative of the central role played by the 1s core hole in inducing charge excitations within the CuO planes. On the other hand, we observe a polarization dependence of the spectral weight, and careful analysis reveals two separate features near 2 eV that may be related to different charge-transfer processes. The polarization dependence indicates that the electrons contribute significantly to the RIXS cross section.