Temperature Evolution of Energy Gap and Band Structure in the Superconducting and Pseudogap States of Bi2Sr2CaCu2O8+δ Superconductor Revealed by Laser-Based Angle-Resolved Photoemission Spectroscopy

• Published in: Chinese physics letters Vol. 35; no. 1; pp. 98 - 102
• Main Author: 孙璇 张文涛 赵林 刘国东 顾根大 彭钦军 王志敏 张申金 杨峰 陈创天 许祖彦 周兴江
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 01.01.2018
• Subjects: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/35/1/017401

We carry out detailed momentum-dependent and temperature-dependent measurements on Bi2Sr2CaCu2O8+δ（Bi2212） superconductor in the superconducting and pseudogap states by super-high resolution laser-based angleresolved photoemission spectroscopy. The precise determination of the superconducting gap for the nearly optimally doped Bi2212（Tc= 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 Bi2Sr2CuO6+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.