Targeting exchange interactions in nanosize molecular magnets by angular momentum technique

Magnetic molecular clusters, that is, molecular assemblies consisting of a finite numbers of exchange coupled ions, represent the class of the so-called zero dimensional magnets.^1–10 These systems are of current interest in many areas of research and applications, like molecular magnetism, molecular spintronics and quantum computing, biochemistry, catalysis (mainly polyoxometalates)^11–13 and have perspective applications as single molecular magnets.^5,14 Organic molecules of increasing sizes and large numbers of unpaired electrons are also being explored as building blocks for molecular-based magnets.^5,6 The modern trend in molecular magnetism is focused on the possibility to use molecular clusters as magnets of nanometer size (so called single molecule magnets), which exhibit magnetic bistability and quantum tunneling of magnetization at low temperatures. These systems are expected to provide the important nano-technological applications as the memory storage elements of molecular size. The magnetic molecular clusters are the main subject of the rapidly developing field of spintronics with promising fascinating applications.^15,16 The promising area of molecular quantum cellular automata has to be also mentioned. The molecular cells are represented by mixed-valence metal clusters with special structures that should have specific properties to be used as molecular cells.^17,18 Recent studies showed that the molecular clusters have a great potentiality as quantum bits of information (qubits) which are expected to give a revolutionary impact to realization of the concept of quantum computing.¹⁹ The understanding of the magnetic and spectroscopic properties of nanoscopic objects between molecules and bulk magnets requires special theoretical concepts. For a long time the treatment....