Common Electronic Features and Electronic Nematicity in Parent Compounds of Iron-Based Superconductors and FeSe/SrTiO$_3$ Films Revealed by Angle-Resolved Photoemission Spectroscopy
1National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 2State Key Lab of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 3Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei 230026 4Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 5Collaborative Innovation Center of Quantum Matter, Beijing 100871
Abstract：We report comprehensive angle-resolved photoemission investigations on the electronic structures and nematicity of the parent compounds of the iron-based superconductors including CeFeAsO, BaFe$_2$As$_2$, NaFeAs, FeSe and undoped FeSe/SrTiO$_3$ films with 1, 2 and 20 layers. While the electronic structure near the Brillouin zone center ${\it \Gamma}$ varies dramatically among different materials, the electronic structure near the Brillouin zone corners ($M$ points), as well as their temperature dependence, are rather similar. The electronic structure near the zone corners is dominated by the electronic nematicity that gives rise to a band splitting of the $d_{xz}$ and $d_{yz}$ bands below the nematic transition temperature. A clear relation is observed between the band splitting magnitude and the onset temperature of nematicity. Our results may shed light on the origin of nematicity, its effect on the electronic structures, and its relation with superconductivity in the iron-based superconductors.
2016, Vol. 33 
