Mössbauer Study of Cubic Phase in the Mn-Sb System

Abstract

One of the methods to produce novel materials is high temperature and high pressure treatment. In such a manner in the Mn Sb system the cubic modi cation of Mn3Sb could be produced [1, 2]. This compound has the L12-type of crystal structure (Cu3Au) with the lattice parameter a = 0.400 nm. The Mn atoms occupy 3c positions with the coordinates (0, 1/2, 1/2), the Sb atoms the positions 1a (0, 0, 0), Fig. 1. In normal conditions, the compound exists in a thermodynamically non-equilibrium state and decomposes at 420 K on the Mn2Sb + Mn phases. The magnetic measurements of the Mn3Sb were performed by the Faraday method in the eld 8.6 kOe and the temperature region from the liquid nitrogen to the temperature of phase decomposition. The derived value of speci c magnetization is very small, ≈ 1.0 A m/kg [2]. The neutron di raction analysis for the Mn3Sb was performed as well [3]. The data obtained were interpreted in the model of the ferrimagnetic ordering of Mn magnetic moments. The magnetic moments of Mn atoms are supposed to be antiparallel and have di erent values initially taking into account the similar local environment of Mn atoms in both tetragonal Mn2Sb and cubic Mn3Sb. However, it is possible to interpret the neutron di raction data in a di erent way, using the model of triangular magnetic ordering of Mn magnetic moments. In contrast to previous one, in this model the Mn atoms are considered to have equal magnetic moments ordered in the (111) plane and forming an equilateral triangle with each moment pointing to the center of the triangle. The similar model was used in [4] to describe the magnetic ordering of Mn in Mn3Pt with the same L12 type of structure below 400 K. Thus the model of the magnetic ordering of Mn atoms in the cubic Mn3Sb is ambiguous. Therefore the purpose of this study was to get Mossbauer information on the number of magnetically nonequivalent states of Mn atoms and to clarify a type of the magnetic ordering in Mn3Sb.