Correspondence between the electronic structure and phase separation in a K-doped FeSe system

C Liu; J L Zhao; J O Wang; H J Qian; R Wu; H H Wang; N Zhang; K Ibrahim

doi:10.1088/1361-648X/aa8156

Correspondence between the electronic structure and phase separation in a K-doped FeSe system

J Phys Condens Matter. 2017 Oct 4;29(39):395503. doi: 10.1088/1361-648X/aa8156. Epub 2017 Jul 21.

Authors

C Liu¹, J L Zhao, J O Wang, H J Qian, R Wu, H H Wang, N Zhang, K Ibrahim

Affiliation

¹ Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China. University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People's Republic of China.

PMID: 28730996
DOI: 10.1088/1361-648X/aa8156

Abstract

Phase separated potassium intercalated FeSe thin films have been synthesized by pulsed laser deposition. The coexistence of FeSe phase and 245 phase was investigated both by x-ray photoemission spectroscopy (XPS) and x-ray diffraction. The volume ratio of these two phases is sensitive to temperatures and amount of extra potassium dosing. The XPS and ultraviolet photoelectron spectroscopy results indicated that these two phases shows the different hybridization strength between adjacent Fe layer and Se layer. We infer that the layered electronic structure is the necessary condition of superconductivity in potassium-doped FeSe system, and the phase separation is driven by competition between quasi-2D and 3D bonding mode within FeSe layer. Similar competition may also be able to interpret the phase seperation in K _x Fe_2-y Se₂ bulk single crystal.