Anomalous Magnetic Moments of Mn₁₃ and Mn₁₉ Clusters

Abstract

Recently, sharply reduced magnetic moments were measured in Mn₁₃ and Mn₁₉ clusters with values of about 0.5 \\micro_B/atom, while other clusters had moments of 1 to 1.4 \\micro_B/atom. It was postulated that this sharply reduced magnetic moment results from the icosahedral growth sequence. We confirm the stability of the icosahedral structures. The icosahedral Mn₁₃ and Mn₁₉ clusters have several nearly degenerate low energy states, each with a low magnetic moment. It is shown that the mixture of ferromagnetic and antiferromagnetic coupling is responsible for the low net magnetic moments.