Low energy impurity kink in the normal and anomalous self-energies in Bi-cuprate superconductors

Abstract

The sharp low energy kink (LEK) in quasiparticle (qp) spectra well below the superconducting energy gap observed in the angle-resolved photo-emission spectroscopy (ARPES) of the Bi-cuprates may be understood in terms of the forward scattering impurities located off the Cu–O planes. The relevance of the idea has been established by comparing the calculated normal self-energy from the off-plane impurity effects and the extracted one from the self-energy analysis of [Formula: see text] (Bi2212) ARPES data in Hong et al. [Phys. Rev. Lett. 113, 057001 (2014)]. In addition to the explanation of the LEK, this is a necessary step to analyze ARPES data, to reveal the spectrum of fluctuations promoting superconductivity. We also present the extracted anomalous self-energy from the self-energy analysis, which is its first experimental determination as far as we are aware of. The extracted anomalous self-energy and its implications are discussed in comparison with the calculated impurity self-energy term.