Chemically Tuning between Ferromagnetism and Antiferromagnetism by Combining Theory and Synthesis in Iron/Manganese Rhodium Borides

Quaternary rhodium borides of general formula A2MRh5B2 (see picture: Mg green, Mn red, Rh blue, B yellow) offer a nice playground for combined synthetic–theoretical investigations. The relative robustness of the underlying structure type allows various adjustments of the valence‐electron concentration to be explored. In synthesizing new magnetic materials by following a chemical theory of cooperative magnetic phenomena, it is demonstrated how physical properties, such as antiferromagnetic or ferromagnetic behavior can be understood, predicted, and, eventually, realized.