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

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Quasiparticle interference (QPI) is a key technique for studying electronic states near the Fermi level and superconducting gaps in unconventional superconductors.
• Iron pnictides, exhibiting a metallic spin-density wave state, serve as a model system to explore complex electronic behaviors.

Purpose of the Study:

• To demonstrate that QPI can probe the interplay between electronic bandstructure and correlation effects in iron pnictides.
• To investigate how QPI patterns inform the selection of realistic tight-binding models by constraining interaction parameters.
• To compare the model-dependent behavior of QPI across different five-orbital models and their sensitivity to the Coulomb interaction parameter (U).

Main Methods:

• Utilizing quasiparticle interference (QPI) analysis.
• Comparing experimental observations with theoretical predictions from three widely used five-orbital models.
• Evaluating the sensitivity of QPI patterns to the Coulomb interaction parameter (U) within each model.

Main Results:

• QPI patterns exhibit model-dependent behavior and varying sensitivity to the Coulomb interaction parameter (U).
• The Ikeda et al. model shows QPI patterns robust to changes in U, with modulation vectors consistent with experimental antiferromagnetic arrangements.
• Other models display higher sensitivity to U, leading to deviations in modulation vectors from experimental data; none fully replicate the observed nearly one-dimensional modulation.

Conclusions:

• QPI is a powerful tool for understanding electronic correlations and bandstructure in metallic spin-density wave states.
• The Ikeda et al. model provides a more consistent description of experimental QPI data in iron pnictides compared to other models.
• The experimental observation of suppressed one-dimensional modulation suggests a reduced role for Dirac points in the studied iron pnictides.