Enhanced Friedel oscillations by nematic fluctuations in an iron-based superconductor

Nematic fluctuations are known to provide an additional superconducting pairing channel which is considered as a possible explanation for the large critical temperatures in iron-based superconductors. We study its influence on the impurity scattering using a minimal microscopic model of nematic fluctuations in an effective two-band system of conduction electrons. Applying a projective renormalization method to integrate out the nematic interaction we find that the impurity scattering potential can be strongly renormalized at small scattering momentum through virtual particle-hole excitations in the d${}_{xz}$/d${}_{yz}$ orbital channel. For the particular material LiFeAs we explicitly calculate the Fourier-transformed local density of states and find excellent agreement with recent scanning tunneling experiments where resonantly enhanced Friedel oscillations have been attributed to the first spectroscopic evidence of nematic fluctuations in an iron-based superconductor.