Insight into interplay between bandstructure and Coulomb interaction via quasiparticle interference.

Abstract

Quasiparticle interference has been used frequently for the purpose of unraveling the electronic states in the vicinity of the Fermi level as well as the nature of the superconducting gap in the unconventional superconductors. Using the metallic spin-density wave state of iron pnictides as an example, we demonstrate that the quasiparticle interference (QPI) can also be used as a probe to provide crucial insight into the interplay of the electronic bandstructure and correlation effects in addition to bringing forth the essential features of electronic states in the vicinity of the Fermi level. Our study reveals that the features of QPI pattern can help us narrow down the interaction parameter window and choose a more realistic tight-binding model. For the three widely used five-orbital models, we find a model-dependent behavior of the QPI together with a different degree of sensitivity to the largest Coulomb interaction parameterU. The patterns in the model of Ikedaet alare relatively robust against change inU,and the real-space modulation vector along the direction with antiferromagnetic arrangement of magnetic moments is consistent with the experiments. The rest of the models show a higher degree of sensitivity toU,and the modulation vector deviates from the experiment. On the other hand, for a realistic range ofU, none of the models exhibit nearly one-dimensional modulation as observed in the experiments, clearly indicating a suppressed role played by the Dirac points, which, otherwise, could have led to a one-dimensional pattern in the absence of additional pockets.