Electronic structure of UGe${}_2$ at ambient pressure: comparison with X-ray photoemission spectra

Abstract

Based on experimental crystallographic data, electronic structure of UGe${}_2$ have been calculated and compared with our results of X-ray photoelectron spectroscopy (XPS) measurements. We employed two different advanced full potential (FP) methods: FP-local-orbital (FPLO) and FP-linear augmented plane waves (Wien2k) codes for non-magnetic and ferromagnetic states. Starting from the local spin-density approximation (LSDA) or generalised gradient approximation (GGA), we verified either the orbital polarisation (OP) correction or the GGA+U approach for the U 5f-electrons, changing Coulomb-repulsion energies U in the range 0-4 eV. Satisfying agreement was achieved between experimental and our calculated magnetic moments using ab-initio LSDA+OP and non-ab-initio GGA+U approaches, the latter for realistic U values of 2-3 eV. We proved by the LSDA+OP approach an existence of the Fermi surface nesting vector along the a axis, possibly responsible for the triplet superconducting pairing. The calculated data reveal predominantly an itinerant U 5f-electron character of bands near the Fermi level, EF, with only small contributions from the U 6d and Ge 4p states. The experimental XPS spectrum of valence bands (VB) also contains the sharp main 5f-electron peak at EF, a wide hump (around -2 eV), and broad small peaks at higher energies. In the calculated XPS spectrum, the width of the main 5f-electron peak varies between 0.8 and 1.4 eV, depending on a method used in computations, but the hump remains unresolved. A newly observed asymmetric 1-eV satellite in the experimental 4f-core XPS spectrum together with known 3-eV and 7-eV satellites suggest dual behaviour of U-5f-electrons in UGe${}_2$, the feature is inferred also from the VB studies.

References in corpus (8)

• A More Accurate Generalized Gradient Approximation for Solids
• Magnetism, Spin-Orbit Coupling, and Superconducting Pairing in UGe${}_2$
• Theory of Ferromagnetic Superconductivity
• Ferromagnetic superconductivity driven by changing Fermi surface topology
• Coupled CDW and SDW Fluctuations as an Origin of Anomalous Properties of Ferromagnetic Superconductor UGe_2
• Magnetic Properties of a Pressure-induced Superconductor UGe${}_2$
• Stoner gap in the superconducting ferromagnet UGe2
• Ab-initio determination of the localized/delocalized f-manifold in UPd_2Al_3

Cited by in corpus (10)

• Electronic structures of ferromagnetic superconductors ${\mathrm{UGe}}_2$ and $\mathrm{UCoGe}$ studied by angle-resolved photoelectron spectroscopy
• Thermoelectric power quantum oscillations in the ferromagnet UGe${}_2$
• Criticalities in the itinerant ferromagnet UGe${}_2$
• Mechanism for transitions between ferromagnetic and antiferromagnetic orders in $d$-electron metallic magnets
• Effect of substitution La by Mg on electrochemical and electronic properties in La${}_{2-x}$Mg${}_x$Ni${}_7$ alloys: a combined experimental and ab initio studies
• Spin-triplet paired phases inside ferromagnet induced by Hund's rule coupling and electronic correlations: Application to ${\mathrm{UGe}}_2$
• Tricritical wings in UGe${}_2$: A microscopic interpretation
• Electronic structure of CeCo${}_{1-x}$Fe${}_x$Ge${}_3$ studied by X-ray photoelectron spectroscopy and first-principles calculations
• Coexisting Kondo hybridization and itinerant f-electron ferromagnetism in UGe2
• Electronic Structure of UGe${}_{2\pm x}$ Thin Films from Photoelectron Spectroscopy