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
within a similar theoretical framework. Our experimental results are consistent with the Periodic Anderson Model. The evidence of hybridization between conduction band and U5f electron states in USb2 presented above supports this assumption.
4. Conclusions
Our angle-resolved photoemission studies of USb2 crystals, taken with an energy resolution of 24 meV, unambiguously show the dispersion of the U5f – conduction band hybridized bands. The contribution of the 5f electron density of states near the valence band edge and in the binding energy region of 300-600 meV was confirmed by both photoionization cross-section dependencies and resonant photoemission. The dispersion of the band (A) closest to the Fermi edge was found to be 14 meV, whereas the broader structure situated in the binding energy range 300-600 meV shows dispersion between 200 and 260 meV. There is also around 10 meV of dispersion in the normal emission data which is an indication that USb2 has some 3D character. The in-plane bonding appears dominant over the c-axis bonding by virtue of the larger dispersions observed in peak B in-plane.
The results presented show substantive similarities between Ce and U compounds [9] and suggest that a similar theoretical framework might be used to describe these two kinds of correlated f-electron systems. The band-like behavior of the U5f electrons and 6d-5f binding energy sequence are in qualitative agreement with a Periodic Model, including PAM, but other periodic models must be considered.
Acknowledgment
This work was supported by the US Department of Energy, Office of Science, Division of Materials Science and Engineering and under contract W-7405-ENG-82. This work is based upon research conducted at the Synchrotron Radiation Center, University of Wisconsin-Madison, which is supported by the NSF under Award # DMR-0084402.
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