Abstract
Ru L 3 -edge X-ray absorption near-edge structure (XANES) and magnetic studies for Ca 2 RuO 4 antiferromagnetic insulator, Sr 2 RuO 4 p-wave superconductor, CaRuO 3 exchange-enchange-enhanced paramagnetic metal, SrRuO 3 itinerant ferromagnetic metal and BaRuO 3 paramagnetic metal are compared. Although these compounds crystallized with different structural distortions, they possess similar RuO 6 octahedral environment where the Ru 4d orbitals are split into partially filled t 2g bands with four electrons and empty e g bands. Two 2p 3/2 -4d dipole transition peaks are observed with lower energy peak A for transition to unfilled t 2g states and the higher energy peak B to empty e g states. The L 3 -edge absorption intensity, shape and e g -t 2g average band separation ΔE (B-A) is closely related to the variation of RuO 6 distortion, Ru-O d-p hybridization and unfilled Ru 4d band width.