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

• 来源期刊: 中国物理快报（英文版）
• 关键词: @@
• 年，卷（期）: 2018,（1）
• 页码范围: 90-94
• 页数: 5页
• 语种: 英文
• DOI: 10.1088/0256-307X/35/1/017401

摘要

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 Bi2Sr2 CuO6+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.