Prussian blue
One of the most promising groups of molecular photomagnetic materials are Co-Fe Prussian blue analogues (i.e. compounds with the same structure and similar chemical make up to Prussian blue. A Prussian blue analogue has a chemical formula M1-2xCo1+x[Fe(CN)6]•zH2O where x and z are variables (z may be zero) and M is an alkali metal. Prussian blue analogues have a face centre cubic structure.