Electronic Band Gap Reduction in Manganese Carbodiimide: MnNCN

The newly synthesized manganese carbodiimide is antiferromagnetic, green in color, and optically transparent. The electronic properties of MnNCN are relatively unstudied; determining the electronic band gap and understanding the effects of the O2- -> NCN2- substitution is extremely important to use this material for practical applications. We present high-resolution measurements of the local density of electronic states of MnNCN and compare them to spectra simulated using detailed density functional theory calculations. We further show that MnNCN has a larger degree of covalent bonding than MnO and has a reduced indirect electronic band gap of 3.40 +/- 0.20 eV of the charge-transfer type. However, the mechanism for this band gap reduction is not clear and requires further study. In conclusion, MnNCN is a wide band gap, antiferromagnetic semiconductor suitable for applications that currently use MnO but require a smaller electronic band gap.