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Uranium 5 f shell in UPd 2 Al 3 </…

1998; American Physical Society; Volume: 58; Issue: 13 Linguagem: Inglês

10.1103/physrevb.58.8793

1095-3795

A. Yaouanc, P. Dalmas de Réotier, G. van der Laan, A. Hiess, J. Goulon, Claus Neumann, P. Léjay, N. Sato,

Physics of Superconductivity and Magnetism

We report x-ray magnetic circular dichroism (XMCD) measurements performed at the uranium ${\mathrm{M}}_{4,5}$ edges in the paramagnetic phase of the heavy fermion superconductors ${\mathrm{UPd}}_{2}{\mathrm{Al}}_{3}$ and ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}.$ The analysis of the spectra with the first sum rule yields the orbital moment of the $5f$ shell for both compounds. The shape of the dichroic spectrum at the ${\mathrm{M}}_{5}$ edge for the two compounds is qualitatively different: a single lobe is observed for ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ and two lobes are detected for ${\mathrm{UPd}}_{2}{\mathrm{Al}}_{3}.$ This two lobe structure reflects the strong effect of the interaction of the uranium $5f$ electrons with their environment in the latter compound.