Electronic Structure of Heavy Fermion Uranium Compounds Studied by Core-Level Photoelectron Spectroscopy

Abstract

High-energy-resolution core-level and valence-band photoelectron spectroscopic studies were performed for the heavy Fermion uranium compounds UGe2, UCoGe, URhGe, URu2Si2, UNi2Al3, UPd2Al3, and UPt3 as well as typical localized and itinerant uranium compounds to understand the relationship between the uranium valence state and their core-level spectral line shapes. In addition to the main line and high-binding energy satellite structure recognized in the core-level spectra of uranium compounds, a shoulder structure on the lower binding energy side of the main lines of localized and nearly localized uranium compounds was also found. The spectral line shapes show a systematic variation depending on the U 5f electronic structure. The core-level spectra of UGe2, UCoGe, URhGe, URu2Si2, and UNi2Al3 are rather similar to those of itinerant compounds, suggesting that U 5f electrons in these compounds are well hybridized with ligand states. On the other hand, the core-level spectra of UPd2Al3 and UPt3 show considerably different spectral line shapes from those of the itinerant compounds, suggesting that U 5f electrons in UPd2Al3 and UPt3 are less hybridized with ligand states, leading to the correlated nature of U 5f electrons in these compounds. The dominant final state characters in their core-level spectra suggest that the numbers of 5f electrons in UGe2, UCoGe, URhGe, URu2Si2, UNi2Al3, and UPd2Al3 are close to but less than three, while that of UPt3 is close to two rather than to three.

Electronic and magnetic properties of the ferromagnetic superconductor UCoGe

“…This is in agreement with our band structure calculations, 5 f e n is estimated to be 2.92 (in the LSDA calculations) and 2.96 (for the GGA approach), as well as with core level photoelectron spectroscopy [64] which shows that 5 f e n is less than but close to 3. These results invalidate the occurrence of U 4+ ions as suggested from neutron form factor analysis [14].…”

Electronic structure ofThRu2Si2studied by angle-resolved photoelectron spectroscopy: Elucidating the contribution of U5fstates inFujimori1, Kobata2, Takeda3 et al. 2017Phys. Rev. BSelf Cite131150View full textAdd to dashboardCite

“…Pronounced peaks located at E B 1 eV originate mainly from Ru 4d states, which do not contribute majorly to the E F . The AIPES valence-band spectrum of URu 2 Si 2 measured at hν = 800 eV [24] is also shown in the bottom of Fig. 1 (a).…”

Electronic structures of UX3 ( X=Al , Ga, and In) studied by photoelectron spectroscopy

“…In addition to the main line located at E B = 377.0 − 377.3 eV, a weak satellite structure can be observed in the high-bindingenergy side of the main line at about 7 eV (E B ∼ 384 eV). This is called as the 7 eV satellite [32], and it has been observed in many uranium based compounds [30,31]. The core-level spectrum of UAl 3 was superimposed on the spectra of UGa 3 and UIn 3 , as in the case of their valence band spectra.…”