k_{z} Selective Scattering within Quasiparticle Interference Measurements of FeSe

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Quasiparticle interference (QPI) is a powerful probe of a material's electronic structure.
• Traditionally, QPI analysis is limited to two-dimensional (2D) electronic states.
• Surface defects in materials like FeSe can complicate electronic structure interpretation.

Purpose of the Study:

• To investigate whether QPI information is exclusively confined to 2D electronic states.
• To demonstrate that QPI in systems like FeSe captures electronic states with negligible group velocity along the z-axis.
• To reconcile discrepancies between different experimental techniques probing FeSe's electronic structure.

Main Methods:

• Development and application of a three-dimensional (3D) tight-binding model for FeSe.
• Fitting the 3D tight-binding model to experimental photoemission measurements.
• Utilizing a T-matrix formalism to calculate and reproduce experimental QPI scattering dispersion.
• Inclusion of both k_{z}=0 and k_{z}=π electronic states in the theoretical model.

Main Results:

• The study successfully reproduces the experimental QPI scattering dispersion for FeSe.
• The theoretical model, incorporating both k_{z}=0 and k_{z}=π states, accurately matches experimental data.
• This demonstrates that QPI measurements capture electronic states with minimal z-axis group velocity, not just 2D states.

Conclusions:

• QPI measurements are not limited to 2D electronic states and can probe 3D electronic behavior.
• The inclusion of k_{z} states is crucial for accurately interpreting surface-sensitive QPI data, especially in materials like FeSe.
• This work unifies findings from tunneling and photoemission experiments on FeSe, highlighting the importance of considering k_{z} in QPI analysis.