Determination of the magnetic structure of manganese carbodiimide with diffraction experiments using polarized neutrons

Abstract

The magnetic structure of MnNCN, the nitrogen equivalent of MnO, and the first carbodiimide of a non-${d}^{10}$ transition metal ever made, has been determined on the basis of spin-polarized neutron-diffraction data close to absolute zero temperature. The $S=5/2$ moments of the high-spin ${\text{Mn}}^{2+}$ ions lie within the $ab$ hexagonal sheets and exhibit an antiferromagnetic ordering between the sheets along the $c$ axis. Below the N\'eel point (28 K), a temperature-dependent ordering pattern exists due to magnetic frustration inside the sheets, characterized by a varying angle between the moments. A comparison with other magnetic structures reveals that the compact ${\text{NCN}}^{2\ensuremath{-}}$ group is capable of mediating significant spin density needed to ensure relatively strong magnetic communication in view of a large ${\text{Mn}}^{2+}\text{--}{\text{Mn}}^{2+}$ separation.