Electronic and magnetic structure of rare-earth materials studied by high-resolution photoemission

Abstract

Recent experimental results concerning the surface and bulk electronic and magnetic structure of rare-earth (RE) metals are presented. Surface core-level shifts in photoemission (PE) and inverse photoemission (IPE) experiments are discussed to summarize the phenomena that occur due 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, leading to essentially no observable shift in PE. Resonant PE experiments with varying degree of surface sensitivity have been performed to investigate 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 for the surface properties are discussed. Single-crystalline RE surfaces open up the possibility to study their magnetic properties as shown for the case of Gd, where a strong magnetic circular dichroism has recently been observed.