Neutron diffraction study of the magnetic structure of α-Mn2O3

The magnetic ordering of alpha-Mn2O3 has been studied by neutron powder diffraction measurements. An antiferromagnetic ordering occurs with the magnetic unit cell equivalent to the crystalline unit cell. Our results are compared with the results of previous works. The main antiferromagnetic Bragg peaks have different temperature dependence of their intensities, suggesting that the magnetic ordering in alpha-Mn2O3 cannot be described by a single order parameter. The temperature dependence of magnetization near 0 K for these peaks differs from Bloch's T-3/2 law. The majority of the magnetic peaks disappear at 80 K, which was reported earlier as the Ndel temperature. The (100) peak, forbidden in the crystal structure of alpha-Mn2O3 is present up to 100 K. A new collinear model of the magnetic ordering of alpha-Mn2O3 at 10 K is presented. (C) 2003 Elsevier B.V. All rights reserved.