Magnetic Structures of Mn2As and Mn2Sb0.7As0.3

Abstract

Neutron diffraction has been performed on powder specimens of Mn₂As and Mn₂Sb_0.7As_0.3. Mn₂As has the antiferromagnetic structure found in Mn_1.9Cr_0.1Sb below the exchange inversion temperature. The atomic moments are 3.7 and 3.5 Bohr magnetons for Mn(I) and Mn(II), respectively. The moments lie perpendicular to the tetragonal axis. The magnetic structure of Mn₂Sb_0.7As_0.3, which undergoes exchange inversion over the 35° to 115°C temperature range, is the same as that of Mn₂As at room temperature and is the same as that of ferrimagnetic Mn₂Sb at 150°C. The atomic moments at room temperature (antiferromagnetic) are 2.3 and 2.8 Bohr magnetons, respectively, for Mn(I) and Mn(II). The moments are perpendicular to the tetragonal axis at room temperature and parallel to it at 150°C.