title: Charge redistribution and a shortening of the Fe--As bond at the quantum critical point of SmO1-xFxFeAs.
abstract: Many researchers have pointed out that there is a quantum critical point (QCP) in the F-doped SmOFeAs system. In this paper, the electronic structure and local structure of the superconductive FeAs layer in SmO(1-x)FxFeAs as a function of the F-doping concentration have been investigated using Fe and As K-edge X-ray absorption spectroscopy. Experiments performed on the X-ray absorption near-edge structure showed that in the vicinity of the QCP the intensity of the pre-edge feature at the Fe-edge decreases continuously, while there is a striking rise of the shoulder-peak at the As edge, suggesting the occurrence of charge redistribution near the QCP. Further analysis on the As K-edge extended X-ray absorption fine structure demonstrated that the charge redistribution originates mostly from a shortening of the Fe-As bond at the QCP. An evident relationship between the mysterious QCP and the fundamental Fe-As bond was established, providing new insights on the interplay between QCP, charge dynamics and the local structural Fe-As bond in Fe-based superconductors.
authors.affiliation: College of Science, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210023, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Information Construction and Management Office, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210023, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Dong
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: Nanjing University (Suzhou) High-Tech Institute, Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Shengli
authors.initials: S
authors.lastname: Liu
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
authors.forename: Wangsheng
authors.initials: W
authors.lastname: Chu
authors.affiliation: Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China.
authors.forename: Xianhui
authors.initials: X
authors.lastname: Chen
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Wu
keywords: XAS; electronic structure; iron-based superconductor; local structure; quantum critical point