Various experiments on UPd3, the analogue of the heavy fermion superconductor, UPt3, have ascertained that there are two f electrons per U which are localized in a magnetic singlet state. Recently, both photoemission (PES) and de Haas-van Alphen (dHvA) experiments have been reported on UPd3. To complement this experimental work, local density energy band calculations have been performed on UPd3 where the f electrons have been treated as core states. The resulting density of states is found to be in good agreement with photoemission data. The theoretical Fermi surface is found to be more complex than current dHvA data indicate, but one can still unambiguously assign theoretical extremal orbits to the experimental data. Thus again, the data is consistent with a local f2 configuration. Since the band calculations can explain the dHvA data in heavy fermion UPt3 with the f electrons treated as band states, one finds that the Kohn-Sham ansatz for treating the f electrons as Bloch states breaks down between these two cases. This finding is confirmed by recent U(PdxPt3-x) alloy experiments which show a sudden decrease in the specific heat coefficient when alloying these two compounds.
ASJC Scopus subject areas
- Condensed Matter Physics