A Note on the Magnetic Structure of KMnF3

The magnetic structure of KMnF 3 has been deduced from group-theoretical consideration based on the new space group P 4/ m b m . In the uniaxial antiferromagnetic region, the structure is of the G-type with the sublattice magnetization parallel to the z axis, while in the weak-ferromagnetic region the structure is of the pseudo-G-type with the sublattice magnetization nearly parallel to the x (or y ) axis and slightly canted towards the y (or x ) axis. These proposed structures are examined by trying an interpretation of the magnetic torsion curves given by Heeger et al. [Phys. Rev. 123 (1961) 1652]. By taking the crystallographic and magnetic domain structures into account, it is shown that the new magnetic structures are fully consistent with the torsion curves including the magnetic-field dependence.