Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temperature T range from 10 K to 675 K. These measurements demonstrate that this compound exhibits collinear antiferromagnetic ordering below the Neel temperature T_N = 625(1) K. The ordered moment mu = 3.88(4) mu_B/Mn at T = 10 K is oriented along the c axis and the magnetic structure is G-type, with all nearest-neighbor Mn moments antiferromagnetically aligned. The value of the ordered moment indicates that the oxidation state of Mn is Mn^{2+} with a high spin S = 5/2. The T dependence of mu suggests that the magnetic transition is second-order in nature. In contrast to the closely related AFe2As2 (A = Ca, Sr, Ba, Eu) compounds, no structural distortion is observed in the magnetically ordered state of BaMn2As2.
@article{arxiv.0907.4094,
title = {Nature of the Magnetic Order in BaMn2As2},
author = {Yogesh Singh and M. A. Green and Q. Huang and A. Kreyssig and R. J. McQueeney and D. C. Johnston and A. I. Goldman},
journal= {arXiv preprint arXiv:0907.4094},
year = {2010}
}
Comments
4 pages, 3 figures, 1 table; v2: additional discussion of Mn-Mn interactions; accepted for publication as a Rapid Communication in Phys. Rev. B