Neutron scattering investigation of the magnetic order in single crystalline BaFe2As2

TL;DR

This study uses neutron diffraction on a high-quality single crystal of BaFe2As2 to clarify its magnetic structure, confirming earlier polycrystalline findings and resolving previous conflicting reports.

Contribution

The paper provides definitive neutron diffraction data from a single crystal that supports the original magnetic structure determination of BaFe2As2, resolving discrepancies in prior studies.

Findings

Magnetic moments align along the a-axis.

Single magnetostructural transition at ~140 K.

Results support earlier polycrystalline data.

Abstract

The magnetic structure of BaFe2As2 was completely determined from polycrystalline neutron diffraction measurements soon after the ThCr2Si2-type FeAs-based superconductors were discovered. Both the moment direction and the in-plane antiferromagnetic wavevector are along the longer a-axis of the orthorhombic unit cell. There is only one combined magnetostructural transition at about 140 K. However, a later single-crystal neutron diffraction work reported contradicting results. Here we show neutron diffraction results from a clean single crystal sample, grown by a self-flux method, that support the original polycrystalline work.