作者
D. Takegami,Chang Yang Kuo,Keito Kasebayashi,J.-G. Kim,C. F. Chang,C. E. Liu,ChenChung Wu,Deepa Kasinathan,S. G. Altendorf,Katharina Hoefer,Federico Meneghin,Andrea Marino,Yen-Fa Liao,Ku‐Ding Tsuei,C. T. Chen,K.-T. Ko,Armin Günther,Stefan G. Ebbinghaus,Jin Won Seo,D. H. Lee,Gihun Ryu,A. C. Komarek,Satoshi Sugano,Yuichi Shimakawa,A. Tanaka,T. Mizokawa,J. Kuneš,L. H. Tjeng,Atsushi Hariki
摘要
We present a comprehensive study of CaCu$_3$Ru$_4$O$_{12}$ using bulk sensitive hard and soft x-ray spectroscopy combined with local-density approximation (LDA) + dynamical mean-field theory (DMFT) calculations. Correlation effects on both the Cu and Ru ions can be observed. From the Cu $2p$ core level spectra we deduce the presence of magnetic Cu$^{2+}$ ions hybridized with a reservoir of itinerant electrons. The strong photon energy dependence of the valence band allows us to disentangle the Ru, Cu, and O contributions and thus to optimize the DMFT calculations. The calculated spin and charge susceptibilities show that the transition metal oxide CaCu$_3$Ru$_4$O$_{12}$ must be classified as a Kondo system and that the Kondo temperature is in the range of 500-1000 K.