Angle-resolved photoemission study of USb2 the 5f band struc(10)

Single crystal antiferromagnetic USb2 was studied at 15K by angle-resolved photoemission with an overall energy resolution of 24 meV. The measurements unambiguously show the dispersion of extremely narrow bands situated near the Fermi level. The peak at th

transition probabilities from the almost pure U5f states at E F than from hybridized U5f bands.

One should remember that resonant photoemission data have qualitative rather than quantitative character. This is due to the different kinds of Auger processes that occur in rare earth and actinide materials [30] (because of the vicinity of partially occupied f and d shells) which give rise to additional decay channels. In uranium-bearing materials there are unique Auger processes based on 5f→E F transition [31], so the resonant Auger decay can be comparable in strength to direct resonant photoemission. Taking into account all of the processes mentioned above it is clear that in the case of uranium compounds the resonant photoemission experiment provides qualitative information about conduction band-5f hybridization. Also, the reduced momentum resolution at photon energies over 100 eV precludes observation of the subtle U5f changes. However, the resonant photoemission experiment confirms that the A and B photoemission peaks have conduction band and 5f origin, giving evidence of conduction band-5f hybridization.

Our results show that the near E F 5f photoemission features of USb2 behave in a way similar to the 4f features of Ce compounds. For example, the ARPES spectra of CeBe13 [10], CeSb2 [8] and CePt2.2 [32] show a sharp 4f peak near the Fermi edge. For CeBe13 the evidence for dispersion of the 4f band was found for two directions of the Brillouin zone. In the case of CeSb2 the dispersion, if present, is expected not to be larger than 10 meV. However, both the 4f5/2 and 4f7/2 bands are strongly momentum dependent, suggesting band-like behavior.

One could expect differences between USb2 and CeSb2 in the location of Sb5p states as is the case of USb and CeSb [24-26]. In CeSb the Sb5p electrons are located closer to the valence band edge because of their different energy position relative to the bare 4f state. However, this assumption needs to be verified by the comparison of photoemission results with theoretical calculations. The near Fermi level part of the electronic structure of USb2 and CeSb2, as seen in photoemission experiment, is indeed similar. Ce and U heavy fermion compounds display similar bulk properties and similar band structure as well. Therefore it is reasonable to assume that they might be described

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