Observation of multiple gaps and vortex bound states in Ba0.6K0.4Fe2As2 by Scanning Tunneling Microscopy/Spectroscopy
ORAL
Abstract
We report on low-temperature scanning tunneling microscopy/spectroscopy studies of the electronic structure in single crystalline Ba0.6K0.4Fe2As2. Multiple superconducting gaps were observed in the density of states (DOS) and the sizes of the two dominant gaps are 7.6 meV and 3.3 meV, respectively. The flat bottom of the DOS spectra near zero bias indicates the nodeless feature of the gaps, while the global fitting to the spectra requires definitely the anisotropy. By applying magnetic fields, we observed ordered vortices with Andreev bound states in vortex cores. The bound states and their spatial evolution can be qualitatively explained by our numerical calculations when considering the multiband s-wave superconductivity.
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Authors
Lei Shan
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Yong-Lei Wang
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Bing Shen
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Bin Zeng
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Jing Gong
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Yan Huang
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Huan Yang
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Cong Ren
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Hai-Hu Wen
Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Ang Li
Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5002, USA
Shuheng Pan
Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5002, USA
Da Wang
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
Qiang-Hua Wang
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
