High-resolution low-temperature photoemission spectroscopy has been performed for UNi2Al3 and URu2Si2 to study the nature of 5f electrons in U-based heavy fermion materials. Photoemission spectra of both compounds have a sharp peak at EF and a large broad peak around 2 eV, while only UNi2Al3 exhibits an additional small broad feature at 0.6 eV. The two features in the vicinity of EF (the EF-peak and the small structure at 0.6 eV) are found to have a dominant U 5f character while the prominent peak around 2 eV is due to the Ni 3d or Ru 4d states. Comparison with the band structure calculations and experimental results on UPd2Al3 suggests that the EF-peak is ascribed to itinerant U 5f electrons while the following broad feature at 0.6 eV represents localized f electrons.
- 5f electrons
- Electronic structure
- High-resolution photoemission spectroscopy
- Uranium compounds