Electronic structures of LaB6 and CeB6 single crystals: X-ray absorption near-edge structure studies at the B K-edge and the La and Ce giant resonance

High resolution X-ray absorption near-edge structures (XANES) of rare earth hexaboride (LaB6 and CeB6) single crystals have been studied at the regions of the B K-edge and the La and Ce N5,4-edge. The difference in the occupancy of 4f electrons between the ground state of La (4d104f0) and Ce (4d104f1) causes different features in the La and Ce N5,4-edge XANES (giant resonance), while B K-edge XANES exhibit similar features for the two materials indicating that the influence of the 4f electron is confined in the vicinity of the lanthanide ion. Theoretical simulations based on density functional theory using the WIEN2k code have been conducted to compare with the XANES at B K-edge. The results and their implications are discussed.