Coexisting on- and off-center Yb3+ sites in Ce1-xYbxFe4P12 skutterudites

Electron Spin Resonance (ESR) measurements performed on the filled skutterudite system Ce1-x$YbxFe4P12 (x 15 GHz) rattling frequency, respectively. Our findings introduce Yb3+ in Th symmetry systems and uses the Yb3+ ESR as a sensitive microscopic probe to investigate the Yb3+ ions dynamics.