Neutron scattering investigation of the magnetic order in single crystalline BaFe₂As₂

The magnetic structure of BaFe₂As₂ was 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 ∼140 K. However, a later single-crystal neutron diffraction work reported contradicting results. Here, we show neutron diffraction results from a single-crystal sample, grown by a self-flux method, that support the original polycrystalline work.