ARPES Spectra of Bi2212 give the Coulomb Coupling ${\lambda }^C\approx 1$ and the Electron-Phonon Coupling ${\lambda }^{EP}=2-3$

Abstract

We show that the double kink-structure in the electronic self-energy of Bi2212 near the nodal point at low energy ${\omega }_1\approx 50-70$ $meV$ and at high energy at ${\omega }_2\approx 350$ $meV$, observed recently in the ARPES measurements by Valla et al \cite{Valla-2006}, gives that the electron-phonon (EPI) coupling constant ${\lambda }_z^{EP}$in the normal part of the self-energy $\Sigma (\omega )$ is twice larger than the Coulomb coupling ${\lambda }_z^C$. The experimental data for $\func{Re}Σ(ω)$ up to energies $\sim 350$ $meV$ can be satisfactory explained by and ${\lambda }_z^C\approx 1.1$. Additionally the low energy slope of the ARPES $\func{Re}Σ(ω)$ at $\omega <20$ $meV$ \cite{Valla-2006} gives a hint that the low energy phonons might contribute significantly to the EPI coupling, i.e. ${\lambda }_z^{low,EP}>1$, thus giving the total EPI coupling constant ${\lambda }_{z,tot}^{EP}={\lambda }_z^{EP}+{\lambda }_z^{low,EP}>3$. In order to test the role of low frequency phonons by ARPES measurements a much better momentum resolution is needed than that reported in \cite{Valla-2006}. Possible pairing scenarios based on ARPES, tunnelling and magnetic neutron scattering measurements are discussed.

arXiv comment4 pages, 1 figure