Temperature Evolution of Energy Gap and Band Structure in the Superconducting and Pseudogap States of Bi₂Sr₂CaCu₂O_8+δ Superconductor Revealed by Laser-Based Angle-Resolved Photoemission Spectroscopy

Journal Article · 17 December 2017 · Chinese Physics Letters

DOI: https://doi.org/10.1088/0256-307X/35/1/017401 · OSTI ID:1430861

Sun, Xuan ^[1]; Zhang, Wen-Tao ^[2]; Zhao, Lin ^[2]; Liu, Guo-Dong ^[2]; Gu, Gen-Da  ^[3]; Peng, Qin-Jun ^[4]; Wang, Zhi-Min ^[4]; Zhang, Shen-Jin ^[4]; Yang, Feng ^[4]; Chen, Chuang-Tian ^[4]; Xu, Zu-Yan ^[4]; Zhou, Xing-Jiang ^[5]

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1. Univ. of Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed Matter Physics and National Lab. for Superconductivity
2. Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed Matter Physics and National Lab. for Superconductivity
3. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics
4. Chinese Academy of Sciences (CAS), Beijing (China). Technical Inst. of Physics and Chemistry
5. Univ. of Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed Matter Physics and National Lab. for Superconductivity; Collaborative Innovation Center of Quantum Matter (CICQM), Beijing (China)

For this study, we carry out detailed momentum-dependent and temperature-dependent measurements on Bi₂Sr₂CaCu₂O_8+δ (Bi2212) superconductor in the superconducting and pseudogap states by super-high resolution laser-based angle-resolved photoemission spectroscopy. The precise determination of the superconducting gap for the nearly optimally doped Bi2212 (T_c=91 K) at low temperature indicates that the momentum-dependence of the superconducting gap deviates from the standard d-wave form (cos(2Φ)). It can be alternatively fitted by including a high-order term (cos(6Φ)) in which the next nearest-neighbor interaction is considered. We find that the band structure near the antinodal region smoothly evolves across the pseudogap temperature without a signature of band reorganization which is distinct from that found in Bi₂Sr₂CuO_6+δ superconductors. This indicates that the band reorganization across the pseudogap temperature is not a universal behavior in cuprate superconductors. These results provide new insights in understanding the nature of the superconducting gap and pseudogap in high-temperature cuprate superconductors.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Key Research and Development Program of China; National Natural Science Foundation of China (NSFC); National Basic Research Program of China; Chinese Academy of Sciences
• Grant/Contract Number: SC0012704; 2016YFA0300300; 11334010; 2015CB921300; XDB07020300
• OSTI ID: 1430861
• Report Number(s): BNL-203394-2018-JAAM
• Journal Information: Chinese Physics Letters, Vol. 35, Issue 1; ISSN 0256-307X
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English