Molecular magnet

Molecular magnets are systems where a permanent magnetization and magnetic hysteresis can be achieved (although usually at extremely low temperatures) not through a three-dimensional magnetic ordering, but as a purely one-molecule phenomenon.

The requisites for such a system are:

• a high spin ground state
• a high zero-field-splitting (due to high magnetic anisotropy)

The combination of these properties can lead to an energy barrier, so that, at low temperatures, the system can be trapped in one of the high-spin energy wells.

Molecular magnets exhibit an increasing product (magnetic susceptibility times temperature) with decreasing temperature, and can be characterized by a shift both in position and intensity of the a.c. magnetic susceptibility.

The first molecular magnet was a dodecanuclear manganese complex, which is held together by oxo-bridges and acetate anions.

Molecular magnets are interesting both from a purely theoretical point of view, for their quantum behavior, and from a practical point of view, as candidates for quantum computing qubits.