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.
@article{arxiv.1010.3545,
title = {Quasiparticle interference in an iron-based superconductor},
author = {Steffen Sykora and Piers Coleman},
journal= {arXiv preprint arXiv:1010.3545},
year = {2011}
}