Quasiparticle interference in an iron-based superconductor

TL;DR

This paper models how magnetic fields influence quasiparticle interference in iron-based superconductors, revealing that Pauli limiting enhances certain scattering features and affects the interpretation of superconducting gap signs.

Contribution

It introduces a simple two-band BCS model to analyze magnetic field effects on quasiparticle interference in iron-based superconductors, focusing on spin-split spectra.

Findings

Magnetic field induces time reversal odd scattering in Fe(Se,Te)

Pauli limiting enhances sign-preserving quasiparticle interference peaks

Magnetic field suppresses sign-reversing interference features

Abstract

We develop a model for the effect of a magnetic field on quasiparticle interference in an iron-based superconductor. Recently, scanning tunneling experiments have been performed on Fe(Se,Te) to determine the relative sign of the superconducting gap from the magnetic-field dependence of quasiparticle scattering amplitudes. Using a simple two-band BCS model, we study three different cases of scattering in a spin-split spectrum. The dominant effect of a magnetic field in iron-based superconductors is caused by the Pauli limiting of conduction electrons. Thereby time reversal odd scattering is induced which enhances the sign-preserving and depresses the sign-reversing peaks in the quasiparticle interference patterns.