The electronic structure of CeNiGe3 and YNiGe3 superconductors by ab initio calculations

Winiarski, M.; Samsel‐Czekała, M.

doi:10.1016/j.ssc.2013.10.027

Cited by 6 publications

(4 citation statements)

References 25 publications

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“…As was previously suggested [52] and later measured [34] for YbNiSi 3 , the three bands collectively indicate that these compounds are good conductors along the [100] and [001] crystallographic directions but not along [010]. Our electronic structure results for both compounds also demonstrate their similarity to the isostructural compound YNiGe 3 [29]. Figure 11 provides a visual representation of the calculated FS of these compounds.…”

Section: Theoretical Resultssupporting

confidence: 78%

“…In the RNiGe 3 (R = Y, Ce) (where R represents rare earth) series [28,29] with a centrosymmetric orthorhombic structure, the compounds YNiGe 3 [30] and CeNiGe 3 [31][32][33] are superconductors. The former has an unusually low specific heat jump at the transition compared to the prediction of BCS theory [30], whereas the latter is an unconventional heavyfermion superconductor under pressure.…”

Section: Introductionmentioning

confidence: 99%

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Superconductivity in monocrystalline YNiSi3 and LuNiSi3

et al. 2019

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We report the discovery of bulk superconductivity in the ternary intermetallics YNiSi 3 and LuNiSi 3. High-quality single crystals were grown via the Sn-flux method and studied using magnetization, specific-heat, and resistivity measurements at low temperatures. The critical temperatures obtained from these different techniques are in very good agreement and yield T c = 1.36(3) K and T c = 1.61(2) K for YNiSi 3 and LuNiSi 3 , respectively. Magnetization measurements indicate that both compounds are among the rare cases where type-I superconductivity occurs in a ternary intermetallic, however, the jump in the specific heat at the transition is lower than the value expected from BCS theory (C el /γ n T c = 1.43) in both materials and is equal to 1.14(9) and 0.71(5) for the Y and Lu compounds, respectively. Resistivity measurements exhibit sharp transitions but with critical fields μ 0 H c (0) (≈0.05 T for YNiSi 3 and ≈0.08 T for LuNiSi 3) considerably higher than those obtained from the magnetization and specific heat (≈0.01 T). First-principles density functional theory calculated electronic structure shows that these compounds have highly anisotropic and complex Fermi surfaces with one electronic and two holelike branches. One hole branch and the electron branch have a large cylindrical topology connecting the first Brillouin-zone boundaries, the former being built up by the hybridization of Y(Lu) d, Ni d, and Si p states, and the latter being built up by Ni d and Si p states. The calculated phononic structures indicate that the coupling of the Y(Lu), Ni d, and Si p electrons in the low-lying optical phonon branches is responsible for the formation of Cooper pairs and the observed superconducting state. Therefore, these compounds can be classified as anisotropic three-dimensional metals with multiband superconducting ground states in the weak-coupling regime.

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Section: Theoretical Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Superconductivity in monocrystalline YNiSi3 and LuNiSi3

et al. 2019

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“…The holelike sheets I-II exhibit 3D character, whereas the electronlike sheets II-IV are cylindrical (quasi-2D). Interestingly, similar electronlike FS sheets have been revealed in other Pd-Ge intermetallics adopting similar structures, e.g., La 3 Pd 4 Ge 4 (I mmm) [17] and LaPdGe 3 (I 4mm) [21], as well as the iron-based YFe 2 Ge 2 [20], and orthorhombic YNiGe 3 (Cmmm) [22].…”

Section: Resultssupporting

confidence: 62%

Electronic Structure of Sr(Pt;Pd)2Ge2 Superconductors by Ab Initio Calculations

Winiarski

2015

J Supercond Nov Magn

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Electronic structures of SrPt 2 Ge 2 and SrPd 2 Ge 2 superconductors have been calculated with the use of the full-potential local-orbital method within the density functional theory. The investigations were focused on analyses of differences between electronic properties of both studied intermetallics that could explain the enhancement of superconducting properties in the former one. The results indicate that the band structures in the vicinity of the Fermi level for both considered compounds are indistinguishable. Meanwhile, the calculated value of the density of states at the Fermi level for SrPt 2 Ge 2 is lower than that of SrPd 2 Ge 2 , thus the significantly higher value of T c in the Pt-based system should be related to an anomalous enhancement of electron-phonon coupling.

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“…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.…”

Section: Valence Band Calculationsmentioning

confidence: 99%