Interband Quasiparticle Scattering in Superconducting LiFeAs Reconciles Photoemission and Tunneling Measurements

TL;DR

This paper resolves a paradox between ARPES and QPI measurements in LiFeAs by demonstrating that interband scattering explains the observed differences, supported by quantitative agreement between experimental data and theoretical calculations.

Contribution

It shows that interband scattering accounts for the ARPES-QPI discrepancy in LiFeAs, providing a unified understanding of quasiparticle scattering in this superconductor.

Findings

Interband scattering explains the ARPES-QPI paradox.

Excellent agreement between experimental data and T-matrix calculations.

Disentangling of interband and intraband scattering processes.

Abstract

Several angle resolved photoemission spectroscopy (ARPES) studies reveal a poorly nested Fermi surface of LiFeAs, far away from a spin density wave instability, and clear-cut superconducting gap anisotropies. On the other hand a very different, more nested Fermi surface and dissimilar gap anisotropies have been obtained from quasiparticle interference (QPI) data, which were interpreted as arising from intraband scattering within hole-like bands. Here we show that this ARPES-QPI paradox is completely resolved by interband scattering between the hole-like bands. The resolution follows from an excellent agreement between experimental quasiparticle scattering data and T-matrix QPI calculations (based on experimental band structure data), which allows disentangling interband and intraband scattering processes.