  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.
