Effect of electron-phonon coupling in the ARPES spectra of the tri-layer cuprate Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+\delta}$

TL;DR

This study uses ARPES to analyze how electron-phonon interactions affect the quasi-particle dispersions in a tri-layer cuprate, revealing layer-dependent kink energies and their relation to phonon modes and superconducting gaps.

Contribution

It provides detailed layer-specific ARPES measurements showing the influence of electron-phonon coupling on quasi-particle dispersions in Bi2223, highlighting the role of different phonon modes.

Findings

Inner plane (IP) has a larger kink energy (~100 meV) than the outer plane (OP) (~70 meV).

The large kink energy in IP is due to buckling mode and superconducting gap effects.

Weak kink features suggest interlayer scattering involving phonons and superconducting gaps.

Abstract

Angle-resolved photoemission spectroscopy using tunable low energy photons allows us to study the quasi-particle (QP) dispersions of the inner and outer CuO2 planes (IP and OP) separately in the tri-layer cuprate Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+\delta}$ (Bi2223). The kink energy of the OP band is $\sim$ 70 meV, as observed in various high-$T_c$ cuprates, while that of the IP band is as large as 100 meV in the superconducting (SC) state. This large kink energy is attributed to the $\sim$ 35 meV buckling mode plus the large ($\sim$ 60 meV) SC gap of IP. The IP band also shows a weak kink feature at 70 meV in the SC state. The latter feature can be explained either by the 70 meV half-breathing mode or by the $\sim$ 35 meV buckling-phonon mode plus the $\sim$ 40 meV SC gap of OP if interlayer scattering of QP is involved.