Unexpected Synergy between Magnetic Iron Chains and Stacked B6 Rings in Nb6Fe1−xIr6+xB8.

The synergistic combination of experiment and density functional theory has led to the discovery of the first ferromagnetic material, Nb₆Fe_1−xIr_6+xB₈, containing in its crystal structure iron chains embedded in stacked B₆ rings. The strong ferromagnetic Fe–Fe interactions found in the iron chains induce an unexpected strengthening of the B–B interactions in the B₆ rings. Beside these strong B–B interactions, strong interlayer metal–boron bonds (Ir–B and Nb–B) ensure the overall structural stability of this phase, while the magnetic Fe–Fe interactions are mainly responsible for the observed ferromagnetic ordering below T_C=350 K. [ABSTRACT FROM AUTHOR]