NMR and NQR studies on transition-metal arsenide superconductors LaRu2As2,KCa2Fe4As4F2,and A2Cr3As3  

作　　者：Jun Luo Chunguang Wang Zhicheng Wang Qi Guo Jie Yang Rui Zhou K Matano T Oguchi Zhian Ren Guanghan Cao Guo-Qing Zheng 罗军;王春光;王志成;郭琦;杨杰;周睿;K Matano;T Oguchi;任治安;曹光旱;郑国庆(Institute of Physics,Chinese Academy of Sciences,and Beijing National Laboratory for Condensed Matter Physics,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Department of Physics,Zhejiang University,Hangzhou 310027,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;Department of Physics,Okayama University,Okayama 700-8530,Japan;Institute of Scientific and Industrial Research,Osaka University,Osaka 567-0047,Japan)

机构地区：[1]Institute of Physics,Chinese Academy of Sciences,and Beijing National Laboratory for Condensed Matter Physics,Beijing 100190,China [2]School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Physics,Zhejiang University,Hangzhou 310027,China [4]Songshan Lake Materials Laboratory,Dongguan 523808,China [5]Department of Physics,Okayama University,Okayama 700-8530,Japan [6]Institute of Scientific and Industrial Research,Osaka University,Osaka 567-0047,Japan

出　　处：《Chinese Physics B》2020年第6期462-469,共8页中国物理B（英文版）

基　　金：National Natural Science Foundation of China(Grant Nos.11674377,11634015,and 11974405);the National Key R&D Program of China(Grant Nos.2017YFA0302904 and 2016YFA0300502);J.Y.also acknowledges support by the Youth Innovation Promotion Association of Chinese Academy of Sciences.

摘　　要：We report 75As-nuclear magnetic resonance(NMR)and nuclear quadrupole resonance(NQR)measurements on transition-metal arsenides LaRu2As2,KCa2Fe4As4F2,and A2Cr3As3.In the superconducting state of LaRu2As2,a Hebel–Slichter coherence peak is found in the temperature dependence of the spin-lattice relaxation rate 1/T1 just below Tc,which indicates that LaRu2As2 is a full-gap superperconducor.For KCa2Fe4As4F2,antiferromagnetic spin fluctuations are observed in the normal state.We further find that the anisotropy rate RAF=Tc 1/Tab 1 is small and temperature independent,implying that the low energy spin fluctuations are isotropic in spin space.Our results indicate that KCa2Fe4As4F2 is a moderately overdoped iron-arsenide high-temperature superconductor with a stoichiometric composition.For A2Cr3As3(A=Na,K,Rb,Cs),we calculate the electric field gradient by first-principle method and assign the 75As-NQR peaks to two crystallographically different As sites,paving the way for further NMR investigation.

关 键 词：transition-metal arsenides 3d and 4d orbitals nuclear magnetic resonance iron-based superconductor 

分 类 号：O511[理学—低温物理]