Organic and molecular ferromagnets

Unlike common ferromagnets such as iron, nickel, cobalt or even cobalt-samarium and Nb-Fe-B, it is extremely rare for a discrete molecule, especially an organic or polymeric material, to have cooperative magnetic interactions. Since the mid-1980s a few such materials have been prepared which demonstrate that ferromagnetic interactions can be present in a molecular-based system. The reports have stimulated studies as to the origins as well as to the properties of molecular/organic ferromagnets. Three routes have led to highly magnetic molecular/polymeric materials: (a) chains of isolated alternating radical cations and radical anions, (b) covalently bonded chains containing alternating different metal ions, and (c) covalently bonded chains involving metal ions and nitroxide radicals.