Magnetic order in BaMn2As2 from neutron diffraction measurements

TitleMagnetic order in BaMn2As2 from neutron diffraction measurements
Publication TypeJournal Article
Year of Publication2009
AuthorsSingh Y, Green MA, Huang Q, Kreyssig A, McQueeney RJ, Johnston DC, Goldman AI
Journal TitlePhysical Review B
Date Published09/01
ISBN Number1098-0121
Accession NumberISI:000270383100005
Keywordsa=sr, ba, crystal, sb, superconductivity

Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temperature T range from 10 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 Mn2+ 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 AFe(2)As(2) (A = Ca, Sr, Ba, and Eu) compounds, no structural distortion is observed in the magnetically ordered state of BaMn2As2. Our results indicate that while next-nearest-neighbor interactions are important in the AFe(2)As(2) materials, nearest-neighbor interactions are dominant in BaMn2As2.

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