Gap anisotropy in the angle-resolved photoemission spectroscopy of Bi_2Sr_2CaCu_2O_{8+\delta}

TL;DR

This paper investigates the gap anisotropy in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ using a d-wave model, analyzing the effects of higher harmonics, impurity scattering, and their impact on superconducting properties and ARPES spectra.

Contribution

It introduces a detailed analysis of the effects of including the next harmonic in the d-wave gap on superconducting properties and ARPES spectra in Bi2212.

Findings

Enhanced low-energy excitations increase the density of states at the nodes.

The slope of the superfluid density versus temperature curve increases at low temperatures.

The ARPES leading edge shifts towards higher energy with the inclusion of higher harmonics.

Abstract

The gap anisotropy in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ is revisited in the framework of a d-wave scenario in view of the recent angle-resolved photoemission experiment. Based on a tight-binding fit to the normal state dispersion, a detail analysis on the effects of the inclusion of the next harmonic in the d-wave has been presented. Significant effect has been observed in the superconducting T$_c$. The density of states is linear at the nodes with enhanced weight, caused by a marked increase in the low energy excitaions which affect the thermodynamics considerably. The slope of the $\rho_s - T$ curve in the low temperature regime increases and the specific heat reflects the enhanced entropy at low temperatures. The leading edge of the ARPES energy distribution curves have been calculated and found to shift towards higher energy. The effect of scattering by non-magnetic impurities in this context is also outlined.