Scrutinizing the double superconducting gaps and strong coupling pairing in (Li1−xFex)OHFeSe

• DOI: 10.1038/ncomms10565
• Publication Date: 2016-01-29T10:25:02Z
• Authors: Zengyi Du; Xiong Yang; Hai Lin; Delong Fang; Guan Du; Jie Xing; Huan Yang; Xiyu Zhu; Hai-Hu Wen
• Keywords: Superconductivity (cond-mat.supr-con); Science; Condensed Matter - Superconductivity; Q; 0103 physical sciences; FOS: Physical sciences; 01 natural sciences; 7. Clean energy; Article

In the iron based superconductors, one of on-going frontier studies is about pairing mechanism. The recent interest concerns high temperature superconductivity and its intimate reason in monolayer FeSe thin films. challenge here how double superconducting gaps seen by scanning tunnelling spectroscopy (STS) associate however to only set Fermi pockets angle resolved photoemission (ARPES). recently discovered (Li1-xFexOH)FeSe phase with Tc=40 K provides a good platform check fundamental problems. Here we report STS study on single crystals. spectrum clearly indicates presence anisotropic maximum magnitudes Delta_1=14.3 meV Delta_2=8.6 meV, mimics that film. Further analysis quasiparticle interference (QPI) allows us rule out d-wave gap, for first time assign larger (smaller) gap outer (inner) hybridized associating dxy (dxz/dyz) orbitals, respectively. huge value Delta_1/k_BT_c = 8.7 undoubtedly proves strong coupling mechanism present system.