Electronic structure ofCeNi2Ge2investigated by angle-resolved photoemission and density-functional calculations

Abstract

We present a detailed investigation of the electronic band structure of the heavy Fermion compound CeNi 2 Ge 2 by means of angle resolved photoemission spectroscopy ͑ARPES͒. Measured with high angular and energy resolution, the experimental data from the ͑001͒ surface display several narrow bands close to the Fermi energy. The nature of these bands was identified by a comparison with augmented spherical wave ͑ASW͒ band structure calculations based on density functional theory ͑DFT͒ in the local density approximation ͑LDA͒. In contrast to the results of previous photoemission measurements on in situ prepared films of CeNi 2 Ge 2 we demonstrate that the investigated bands show strong dispersion, in agreement with the theoretical results. In addition we show that the orbital character of the states close to the Fermi level is mainly Ni 3d and that an ''unusual giant Kondo resonance'' does not exist in the photoemission spectra.

Unconventional Superconductivity and Magnetism in Lanthanide and Actinide Intermetallic Compounds

“…They also exhibit quasi-two dimensional character with strong correlations between moments in the [110] planes. The electronic structure was recently studied by angle-resolved photoemission (Ehm et al 2001). The low-temperature data (T ≃ 20 K) exhibit strongly dispersing bands in agreement with LDA band structure calculations.…”

“…PES spectra at various temperatures showing the apperance of the low temperature Kondo resonance in CeCu 2 Si 2 . The inset shows 4f-spectral density ρ 4f (E) of the impurity Anderson model calculated within NCA (Reinert et al, 2001). …”

Electronic structure of the heavy-fermion superconductor Ce2Ni3Ge5 and its reference Ce2Ni3Si5 compound by ab initio calculations

“…Bearing in mind that such a large value of U causes only minor changes around EF, it is clear that the pure LDA approach may also be sufficient for investigations of electronic structures of other Ce-Ni-Ge compounds, e.g. Ce3Ni2Ge7, CeNiGe3 [28], CeNi2Ge2 [29]. Quite a significant hybridization between the Ce 4f and d/p electron orbitals of Ni and Ge atoms can explain the situation that the correct value of the U potential for the Ce 4f states may be even critically low (<0.5 eV) as that deduced for CeRu2Al10 due to its verification by the valence-band x-ray photoemision spectrum [30].…”

Photoemission Study of the Rare Earth Intermetallic Compounds: RNi₂Ge₂ (R=Eu, Gd)

“…By combining the escape angle and the photon energy properly, one can reach the whole Brillouin zone [35]. Therefore, when performing an ARPES experiment at constant photon energy we actually follow a circular path in k space rather than a straight line [36]. The radius of this circle is determined by the equation states near £>, assuming a free-electron final state.…”