Molecular magnets

Magnetic materials in which the fundamental building block is molecular have attracted a great deal of interest because they capitalize on the flexibility inherent in carbon chemistry. Some compounds incorporating chemically stable free radicals are purely organic and show long-range magnetic order at very low temperatures, but the most useful molecular magnets incorporate transition metal or lanthanide ions, with the molecular groups providing a bridge to mediate exchange interactions between the ions. Some of these materials exhibit a spin crossover effect between low-spin and high-spin states. Other molecular magnets form model low-dimensional magnetic compounds that can be used to test models of quantum spin systems. Molecular nanomagnets are complex molecules containing a number of metal ions whose individual moments conspire to create a giant magnetic moment associated with the entire molecule. These systems can be used to exhibit quantum tunnelling of magnetization and are also candidate systems for quantum computing applications.