# Probing the reconstructed Fermi surface of antiferromagnetic BaFe$_2$As$_2$ in one domain

## TL;DR

This study uses high-resolution ARPES to investigate the anisotropic 3D Fermi surface of BaFe$_2$As$_2$ in its magnetic phase, revealing magnetism as the main factor reconstructing its electronic structure.

## Contribution

It provides direct experimental evidence that magnetism, rather than orbital ordering, dominates the electronic reconstruction in BaFe$_2$As$_2$, using nano-ARPES without applied strain.

## Key findings

- Revealed a highly anisotropic 3D Fermi surface in the magnetic phase.
- Showed magnetism as the primary cause of electronic structure reconstruction.
- Demonstrated nano-ARPES can measure band dispersions within a single domain without strain.

## Abstract

We revisit the electronic structure of BaFe$_2$As$_2$, the archetypal parent compound of the Fe-based superconductors, using angle-resolved photoemission spectroscopy (ARPES). Our high-resolution measurements of samples detwinned by the application of a mechanical strain reveal a highly anisotropic 3D Fermi surface in the low temperature magnetic phase. By comparison of the observed dispersions with ab-initio calculations, we argue that overall it is magnetism, rather than orbital ordering, which is the dominant effect, reconstructing the electronic structure across the Fe 3d bandwidth. Finally, we measure band dispersions directly from within one domain without applying strain to the sample, by using the sub-micron focused beam spot of a nano-ARPES instrument.