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A. A. Kordyuk, S. V. Borisenko, M. Knupfer, J. Fink
The kink on the renormalized dispersion along the nodal direction of the superconducting cuprates is widely considered as a key phenomenon for understanding the nature of the main interaction and pairing in the cuprates but, until now, there is no systematic study of constituents that actually form it\x{2014}there is even no agreement how to quantify the kink. At the same time, the kink feature has currently appeared in the focus of the main dilemma about the nature of the glue for the electrons in the cuprates: phonons vs spin-fluctuations. Here we show that careful and systematic analysis of the photoemission data gives a possibility to disentangle two main constituents that form the renormalized dispersion: electronic and bosonic densities of states. We have found that the kink, the phenomenon which we now associate with the scattering to bosonic channel only, appears as a sharp feature on top of a bent caused by the electron-electron interaction. While the coupling to the bosonic mode and, consequently, the kink vanish with overdoping, the bent, being rather sharp due to presence of the van Hove singularity, substitutes the kink for the overdoped samples, faking the persistence of the kink for all doping levels. The dependence of the purified kink on doping, temperature and also parity proves that the spin-fluctuations are the main bosonic scatterer of the quasiparticles in the cuprates. |