Probing the magnetic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>5</mml:mn><mml:mi>f</mml:mi></mml:math>density of states above the Fermi level in metallic uranium compounds by x-ray magnetic circular dichroism

Abstract

We present x-ray magnetic circular dichroism (XMCD) measurements performed at the uranium ${M}_{4,5}$ edges of the heavy-fermion superconductors ${\mathrm{UBe}}_{13}$ and ${\mathrm{UPt}}_{3}.$ Unexpectedly, the dichroic signal at the ${M}_{5}$ edge exhibits a double-lobe structure, comprised of a positive and negative peak. Therefore, out of the eight metallic uranium compounds so far investigated by XMCD, five exhibit a single-lobe and three a double-lobe structure at the ${M}_{5}$ edge. The existence of this structure points to the importance of the influence of the hybridization, Coulomb and exchange, and crystal-field interactions. The observed line shape can be used to access the magnetic character of the $j=7/2$ level of the empty $5f$ density of states.