Magnetic ordering in manganese clusters

Isolated manganese clusters, Mn_n, (n=5–22) are deflected by a linear-gradient magnetic field. Mn₇-Mn₂₂ are found to deflect uniformly toward high field. The magnitude of the deflections indicate susceptibilities far in excess of those expected based on the susceptibility of bulk manganese, demonstrating that Mn clusters in this size range are magnetically ordered. Per-atom moments obtained from Curie’s Law analysis range from 0.4μ_b (Mn₁₉) to 1.7 μ_b (Mn₁₂). For Mn₅ and Mn₆, symmetric broadening of the cluster beam is observed, and their moments were determined via line-shape analysis using both free-spin and adiabatic rotor models. The measured moments, interpreted in light of recent density functional theory calculations, suggest that Mn clusters in this size range are molecular ferrimagnets.