We discover a pressure induced quantum phase transition from the superconducting state to the non-superconducting Kondo screened phase associated with a 2% volume collapse in CeFeAsO0.7F0.3 through measurements of high-pressure resistance, synchrotron x-ray diffraction, and x-ray absorption spectroscopy (XAS) in a diamond anvil cell. Our XAS data of Ce-L3 in CeFeAsO0.7F0.3 clearly show a spectral weight transfer from the main line to the satellite line after the transition, demonstrating the formation of the Kondo singlets under pressure in CeFeAsO1-xFx. Our results have revealed a physical picture of a pressure-induce competition between Kondo singlets and BCS singlets in the Ce-pnictide superconductors.
@article{arxiv.0907.4212,
title = {Evidence for Competition between Superconductivity and Kondo Effect in CeFeAsO0.7F0.3 under High Pressure},
author = {Liling Sun and Xi Dai and Chao Zhang and Wei Yi and enfu Cheng and Nanlin Wang and Lirong Zheng and Zheng Jiang and Xiangjun Wei and Yuying Huang and Jie Yang and Zhian Ren and Wei Lu and Xiaoli Dong and Guangcan Che and Qi Wu and Hong Ding and Jing Liu and Tiandou Hu and Zhongxian Zhao},
journal= {arXiv preprint arXiv:0907.4212},
year = {2015}
}