Superconducting Gap Anisotropy and Quasiparticle Interactions: a Doping Dependent ARPES Study

TL;DR

This study uses ARPES to analyze how quasiparticle interactions and superconducting gap anisotropy in Bi2212 vary with doping, revealing the inadequacy of non-interacting models and the significance of long-range interactions.

Contribution

It provides a doping-dependent analysis of quasiparticle interactions and gap anisotropy, highlighting the limitations of simple d-wave models and estimating the Landau interaction parameter.

Findings

Non-interacting quasiparticle models are inadequate for nodal excitations.

The Landau interaction parameter varies with doping.

The superconducting gap deviates from simple d-wave form in underdoped samples.

Abstract

Comparing ARPES measurements on Bi2212 with penetration depth data, we show that a description of the nodal excitations of the d-wave superconducting state in terms of non-interacting quasiparticles is inadequate, and we estimate the magnitude and doping dependence of the Landau interaction parameter which renormalizes the linear T contribution to the superfluid density. Furthermore, although consistent with d-wave symmetry, the gap with underdoping cannot be fit by the simple coskx-cosky form, which suggests an increasing importance of long range interactions as the insulator is approached.