Electronic Evidence of Unusual Magnetic Ordering in a Parent Compound of FeAs-Based Superconductors

TL;DR

This study uses high-resolution photoemission to reveal unique electronic and magnetic properties in BaFe2As2, a parent compound of FeAs-based superconductors, showing complex band reorganization without a typical gap opening.

Contribution

It provides direct evidence of a magnetic ordering state in BaFe2As2 that differs from conventional spin-density-wave models, highlighting electronic complexity and local magnetic moments.

Findings

No gap opening on the Fermi surface in the magnetic state

Dramatic band structure reorganization across the magnetic transition

Appearance of singular Fermi spots near (pi,pi) as a signature of magnetic ordering

Abstract

High resolution angle-resolved photoemission measurements have been carried out on BaFe2As2, a parent compound of the FeAs-based superconductors. In the magnetic ordering state, there is no gap opening observed on the Fermi surface. Instead, dramatic band structure reorganization occurs across the magnetic transition. The appearance of the singular Fermi spots near (pi,pi) is the most prominent signature of magnetic ordering. These observations provide direct evidence that the magnetic ordering state of BaFe2As2 is distinct from the conventional spin-density-wave state. They reflect the electronic complexity in this multiple-orbital system and necessity in involving the local magnetic moment in describing the underlying electron structure.