摘要
The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.
The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.
作者
Li-Yuan Rong
Xun Shi
Pierre Richard
Yun-Lei Sun
Guang-Han Cao
Xiang-Zhi Zhang
Jun-Zhang Ma
Ming Shi
Yao-Bo Huang
Tian Qian
Hong Ding
Ren-Zhong Tai
荣丽媛;施训;芮夏岩;孙云蕾;曹光旱;张祥志;马均章;史明;黄耀波;钱天;丁洪;邰仁忠(Shanghai Synchrotron Radiation Facility,Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201204;School of Physics,University of Chinese Academy of Sciences,Beijing 100190;Beijing National Laboratory for Condensed Matter Physics and Institute of Physics,Chinese Academy of Sciences,Beijing 100190;Collaborative Innovation Centerof Quantum Matter,Beijing 100084;Department of Physics,Zhejiang University,Hangzhou 310027;paul Scherrer Institut,Swiss Light Source,Villigen PSI CH-5232,Switzerland)
基金
Supported by the National Basic Research Program of China under Grant Nos 2013CB921700,2015CB921300 and2015CB921301
the National Natural Science Foundation of China under Grant Nos 11234014,11622435,11274362,11674371 and11474340
the National Key Research and Development Program of China under Grant Nos 2016YFA0300300,2016YFA0300600,2016YFA0401000 and 2016YFA0400902
the Open Large Infrastructure Research of Chinese Academy of Sciences,and the Pioneer Hundred Talents Program(Type C)of Chinese Academy of Sciences
