Directly visualizing the sign change of d-wave superconducting gap in Bi2Sr2CaCu2O8+δ by phase-referenced quasiparticle interference

Qiangqiang Gu(Collaborative Innovation Center of Advanced Microstructures), Siyuan Wan(Collaborative Innovation Center of Advanced Microstructures), Qingkun Tang(Collaborative Innovation Center of Advanced Microstructures), Zengyi Du(Collaborative Innovation Center of Advanced Microstructures), Huan Yang(Collaborative Innovation Center of Advanced Microstructures), Qiang-Hua Wang(Collaborative Innovation Center of Advanced Microstructures), Ruidan Zhong(Brookhaven National Laboratory), Jinsheng Wen(Brookhaven National Laboratory), Genda Gu(Brookhaven National Laboratory), Hai‐Hu Wen(Collaborative Innovation Center of Advanced Microstructures)
RePEc: Research Papers in Economics
January 1, 2000
Cited by 34

Abstract

Abstract The superconducting state is formed by the condensation of Cooper pairs and protected by the superconducting gap. The pairing interaction between the two electrons of a Cooper pair determines the gap function. Thus, it is pivotal to detect the gap structure for understanding the mechanism of superconductivity. In cuprate superconductors, it has been well established that the gap may have a d-wave function. This gap function has an alternative sign change in the momentum space. It is however hard to visualize this sign change. Here we report the measurements of scanning tunneling spectroscopy in Bi2Sr2CaCu2O8+δ and conduct the analysis of phase-referenced quasiparticle interference (QPI). We see the seven basic scattering vectors that connect the octet ends of the banana-shaped contour of Fermi surface. The phase-referenced QPI clearly visualizes the sign change of the d-wave gap. Our results illustrate an effective way for determining the sign change of unconventional superconductors.

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