[摘要]：Homonuclear cobalt and iron clusters Co(N) and Fe(N) measured in a cryogenic molecular beam exist in two states with distinct magnetic moments (mu), polarizabilities, and ionization potentials, indicating distinct valences. The mu is approximately quantized: mu(N) similar to 2N mu(B) in the ground states and mu(N)* similar to N mu(B) in the excited states for Co; mu(N) similar to 3N mu(B) and mu(N)* similar to N mu(B) for Fe. At a large size, the average mu of the two states converges to the bulk value with diminishing ionization potential differences. The experiments suggest localized ferromagnetism in the two states and that itinerant ferromagnetism emerges from their superposition.
