Changes in 5d band polarization in rare-earth compounds

X-ray resonant magnetic scattering has been used to examine the magnetic interactions coupling the rare earth and iron sublattices in the antiferromagnetic compound DyFe{sub 4}Al {sub 8} . Dramatic differences are observed in the temperature dependencies of the energy profiles at resonance depending on whether the photon energy is tuned to the Dy L{sub 2} or L{sub 3} absorption edge. In particular, for temperatures increasing from 10thinspthinspK, the resonant scattering intensity at the L{sub 3} edge decreases whereas that at the L{sub 2} edge rises. We suggest a physical model capable of reproducing these phenomena. {copyright} {ital 1999} {ital The American Physical Society}