Local structural variation as source of magnetic moment reduction in   BaFe2As2
  We report time-of-flight neutron powder diffraction results on stoichiometric BaFe2As2. Pair distribution function analysis shows that the orthorhombic distortion in the a-b plane at short distances are significantly different from the average lattice distortion, indicating local variations in the lattice at the short-range. We propose that this local variation reflects a high density of nano-twins, short-ranged structures which locally affect the magnetic alignment. This results suggests that the discrepancies between the observed and calculated magnetic moments in BaFe2As2 arise partly from short-ranged variation of the lattice in the a-b plane. 
Jennifer L. Niedziela, M. A. McGuire, T. Egami
cond-mat.supr-con