Magnetic Structure of Mn3O4 by Neutron Diffraction

Mn3O4 is a tetragonal spinel I41/amd. It is ferromagnetic below Tc = 43°K. At 4.2°K neutron diffraction measurements on powdered samples show the presence of 8 sublattices in a unit cell a, 2a, c which is double the chemical unit cell. These 8 sublattices are arranged as follows: 2 sublattices at tetrahedral sites and 6 sublattices at octahedral sites. At 4.2°K the moments are 4.65 μB on A sites and 3.55 μB on B sites with a resulting moment of 1.85 μB/molecule along the (010) direction. The study of thermal variation of the structure shows that at 33°K a rearrangement of moments occurs such that the chemical and magnetic unit cells become identical.