ARPES kink is a 'smoking gun' for the theory of high-Tc superconductors: dominance of the electron-phonon interaction with forward scattering peak

摘要

The ARPES spectra in high-Tc superconductors show four distinctive featuresin the quasiparticle self-energy. All of them can be explained consistently bythe theory in which the electron phonon interaction (EPI) with the forwardscattering peak dominates over the Coulomb scattering. In particular, thistheory explains why there is no shift of the nodal kink at 70 meV in thesuperconducting state, contrary to the clear shift of the anti-nodalsingularity at 40 meV. The theory predicts a ``knee''-like structure of theimaginary part of the self-energy, which is phonon dominated for $\omega\approx \omega^{(70)}_{ph}$, and shows linear behavior for $\omega >\omega^{(70)}_{ph}$ - due to the Coulomb scattering. Recent ARPES spectra givethat the EPI coupling constant is much larger than the Coulomb one. Thedip-hump structure in the spectral function comes out naturally from theproposed theory.