2012/07/30 by Shaolong He, Junfeng He, Wenhao Zhang +21 · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1038/nmat3648
published as Nature Materials 12 (2013) 605-610 · 15 pages, 4 figures
arxiv created 2012/07/30 · arxiv updated 2015/06/05
Superconductivity in the cuprate superconductors and the Fe-based superconductors is realized by doping the parent compound with charge carriers, or by application of high pressure, to suppress the antiferromagnetic state. Such a rich phase diagram is important in understanding superconductivity mechanism and other physics in the Cu- and Fe-based high temperature superconductors. In this paper, we report a phase diagram in the single-layer FeSe films grown on SrTiO3 substrate by an annealing procedure to tune the charge carrier concentration over a wide range. A dramatic change of the band structure and Fermi surface is observed, with two distinct phases identified that are competing during the annealing process. Superconductivity with a record high transition temperature (Tc) at ~65 K is realized by optimizing the annealing process. The wide tunability of the system across different phases, and its high-Tc, make the single-layer FeSe film ideal not only to investigate the superconductivity physics and mechanism, but also to study novel quantum phenomena and for potential applications.