# Nesting-induced Local Electronic Patterns around a Single As (Te, Se) Vacancy in Iron-based Superconductors

## TL;DR

This study explores how single As (Te, Se) vacancies influence local electronic patterns in iron-based superconductors, revealing robust in-gap states and energy-dependent charge modulations linked to Fermi surface nesting.

## Contribution

It demonstrates the impact of vacancies on local electronic states and identifies the origin of charge modulations as Fermi surface nesting effects.

## Key findings

- Vacancies induce two in-gap resonance peaks in LDOS.
- Charge modulations are energy-dependent and related to quasiparticle interference.
- Local electronic patterns are robust and independent of superconducting phase.

## Abstract

The local electronic states around a single As (Te, Se) vacancy are investigated in order to shed light on the role of ligands in a series of iron-based superconductors. Such a vacancy can produce a local hopping correction ranging from $-0.22$ eV to 0.12 eV and always induce two in-gap resonance peaks in the local density of states (LDOS) at the fixed symmetrical bias voltages, which are rather robust and irrelevant to the phase of superconducting order parameter. The LDOS images near the defect predominantly possess $0^o$ and $45^o$ stripes. These energy-dependent charge modulations created by quasiparticle interference are originated in the nesting effect between the inner (outer) hole Fermi surface around $\Gamma$ point and the inner (outer) electron Fermi surface around $M$ point.