Nodal superconducting gap in LiFeP revealed by NMR:Contrast with LiFeAs

作     者：A F Fang R Zhou H Tukada J Yang Z Deng X C Wang C Q Jin Guo-Qing Zheng 房爱芳;周睿;H Tukada;杨杰;邓正;望贤成;靳常青;郑国庆

作者机构：Department of PhysicsBeijing Normal UniversityBeijing 100875China Institute of PhysicsChinese Academy of Sciencesand Beijing National Laboratory for Condensed Matter PhysicsBeijing 100190China Songshan Lake Materials LaboratoryDongguan 523808China Department of PhysicsOkayama UniversityOkayama 700-8530Japan 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2021年第30卷第4期

页      面：113-118页

核心收录：

学科分类：080705[工学-制冷及低温工程] 07[理学] 070205[理学-凝聚态物理] 08[工学] 0807[工学-动力工程及工程热物理] 0702[理学-物理学] 

基　　金：Project supported by the Natioanl Natural Science Foundation of China(Grant Nos.11904023,11974405,11674377,and 11634015) the Fundamental Research Funds for the Central Universities,China(Grant No.2018NTST22) the National Key R&D Program of China(Grant Nos.2016YFA0300502 and2017YFA0302904) the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33010100) 

主　　题：iron-based superconductor nuclear magnetic resonance superconducting pairing symmetry spin fluctuations 

摘      要：Identifying the uniqueness of FeP-based superconductors may shed new lights on the mechanism of superconductivity in ***,we report nuclear magnetic resonance(NMR) studies on LiFeP and LiFeAs which have the same crystal structure but different pnictogen *** NMR spectrum is sensitive to inhomogeneous magnetic fields in the vortex state and can provide the information on the superconducting pairing symmetry through the temperature dependence of London penetration depth λ_(L).We find that λ_(L) saturates below T~0.2 T_(C) in LiFeAs,where T_(C) is the superconducting transition temperature,indicating nodeless superconducting ***,by using a two-gaps model,we simulate the temperature dependence of λ_(L) and obtain the superconducting gaps of LiFeAs,as Δ_(1)=1.2 kB T_(C) and Δ_(2)=2.8 k_(B)T_(C),in agreement with previous result from spin-lattice *** LiFeP,in contrast,λ_(L) does not show any saturation down to T~0.03 T_(C),indicating nodes in the superconducting gap ***,we demonstrate that strong spin fluctuations with diffusive characteristics exist in LiFeP,as in some cuprate high temperature superconductors.