ELECTRONIC AND MAGNETIC-STRUCTURE OF RARE-EARTH MATERIALS STUDIED BY HIGH-RESOLUTION PHOTOEMISSION

Recent experimental results concerning the surface and bulk electronic and magnetic structure of rare-earth (RE) metals are presented. Surfa ce core-level shifts in photoemission (PE) and inverse photoemission ( IPE) experiments are discussed to summarize the phenomena that occur d ue to the energy lowering of 4f states at the surface. In Ce metal, a highly correlated electronic system, surface effects are influenced by the strong interaction of the 4f electron with the valence band, lead ing to essentially no observable shift in PE. Resonant PE experiments with varying degree of surface sensitivity have been performed to inve stigate the surface electronic structure in these systems. With recent progress in the growth of well-ordered epitaxial films of RE metals, detailed band-structure studies have become possible. The existence of a localized d-state at the surface is demonstrated and consequences f or the surface properties are discussed. Single-crystalline RE surface s open up the possibility to study their magnetic properties as shown for the case of Gd, where a strong magnetic circular dichroism has rec ently been observed.