Density of States Driven Anisotropies Induced by Momentum Decoupling in High-Tc Superconductors

TL;DR

This paper explains anisotropies in high-Tc superconductors through momentum decoupling, linking electron-phonon scattering and density of states anisotropies to experimental ARPES and tunneling data.

Contribution

It provides a natural explanation for various experimental observations in Bi-2212 using a momentum decoupling framework with isotropic s-wave interactions.

Findings

Explains gap magnitude and dip visibility correlation in ARPES.

Accounts for temperature-dependent anisotropy enhancement.

Describes gap minima and maxima directions consistent with experiments.

Abstract

Momentum decoupling arises when small momentum transfer processes dominate the electron-phonon scattering and implies that anisotropies in superconductivity are driven by the anisotropies of the density of states. Considering an isotropic s-wave interaction in the momentum decoupling regime we give a natural simultaneous explanation to various aspects of ARPES and tunnel experiments on $Bi_2Sr_2CaCu_2O_8$, including the correlation of gap magnitude and visibility of the dip above the gap, the enhancement of anisotropy with temperature, the presence of gap minima away from the $\Gamma-X$ direction and a gap maximum in the $\Gamma-X$ direction, the similarity of tunnel and ARPES spectra in the $\Gamma-\bar{M}$ direction and the asymmetry in the SIN tunnel spectra where the dip structure is present only at negative sample bias.