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

Abstract

Band structures of the pressure-induced, heavy-fermion superconductor Ce2Ni3Ge5 and its non-superconducting, mixed-valence isostructural (Ibam) counterpart Ce2Ni3Si5 have been calculated employing the full-potential local-orbital code. Both the local density approximation (LDA) and LDA+U approaches were applied. These investigations were focused particularly on the topology of the Fermi surfaces (FSs) of the compounds. The results show that the FSs are quite similar in these systems and exist in four bands, containing three-dimensional holelike and electronlike sheets. However, the specific FS nesting properties has been revealed only in Ce2Ni3Ge5. They support a previously postulated presence of antiferromagnetic spin fluctuations (SF) in the heavy-fermion superconducting state of this germanide under pressure. Such SF can be responsible for the pressure-induced unconventional superconductivity in this system.

Electronic structure, magnetic properties, and mixed valence character of Ce2Ni3Si5 from first principles calculations

“…The DOS at the Fermi level is 2 states/eV. An analysis of the DOS using the PBE functional shows that the predominant contribution to the DOS at the Fermi level is coming from Ce 4f band . There is also a contribution in the DOS at the Fermi level from Ni 3d in addition to a small contribution from Ce 5d and Si 3p states.…”

“…Conversely, for cerium‐based compounds, the ab initio calculations provide useful information about the electronic properties, magnetic properties, mixed valence character, and the topology of the Fermi surfaces . Due to the strongly correlated character of f and d electrons, these electrons are calculated and located wrongly using the density functional theory (DFT) methods such as the local density approximation and the generalized gradient approximation (GGA).…”

Electronic structure of the heavy fermion superconductor Ce2PdIn8: Experiment and calculations

“…The effect of U 4f on the electronic structure of a few Ce-based heavy-fermion superconductors has been studied in details, e.g., for Ce 2 Ni 3 Ge 5 and CeNiGe 3 [53,54], likewise for several non-superconducting Ce-based systems, e.g., CeMo 2 Si 2 C [55] and CeAg 2 Ge 2 [56]. In all those calculations, a shift of less than 1 eV was found of unoccupied Ce 4f states towards higher energies, if strong Coulomb repulsion U on Ce 4f orbitals was applied.…”