Nature of the Magnetic Order in BaMn2As2

TL;DR

This study reveals that BaMn2As2 exhibits high-temperature collinear antiferromagnetic order with a G-type structure and no structural distortion, highlighting its distinct magnetic properties compared to related compounds.

Contribution

The paper provides detailed neutron diffraction analysis showing the magnetic structure and ordering temperature of BaMn2As2, revealing its unique magnetic and structural characteristics.

Findings

Neutron diffraction confirms collinear G-type antiferromagnetic order below 625 K.

The ordered Mn moment is 3.88 μ_B, indicating Mn^{2+} high-spin state.

No structural distortion occurs in the magnetically ordered state.

Abstract

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.