NANOMETER-SIZED STRUCTURES AND THE TRANSITION FROM THE MOLECULAR TO THE SOLID-STATE

The magnetic properties of nanometer-sized molecular complexes that contain an increasing number n of superexchange-coupled iron ions (10 less-than-or-equal-to n less-than-or-equal-to 20) participating in three-dimensional or lower-dimensional magnetic interactions are examined. The experimental criteria that establish the onset of incipient solid-state magnetic correlation effects in these molecules are emphasized. These chemical structures are beyond the molecular realm but convergence to the bulk has not yet been attained. Thus, they afford appropriate experimental systems to test theoretical predictions that the onset of incipient solid-state phenomena-such as the emergence of a conduction band in metallic clusters and collective magnetic interactions responsible for magnetic ordering in solids-occurs in the vicinity of n greater-than-or-equal-to 10, where n is the number of atoms or interacting spins in the cluster.