Spin control in organic molecules

Abstract

Magnetism has fascinated and served humanity for almost 3000 years. Since the discovery of the lodestone (FeO-Fe_2O_3), many different magnetic materials have been developed, almost all based on transition metals and/or rare-earth elements. Technological application of magnetism also has a long history, from the compass to today's sophisticated magnetic memory systems. In contrast, the theory of magnetism has progressed more slowly, despite the efforts of great minds throughout history. The reason early theoretical models were not very valuable is now clear. Any viable theory of magnetism must be based on two inherently quantum mechanical concepts: electron spin and the Pauli exclusion principle. As such, only the 20th century has produced a competent model for magnetism, and that model continues to evolve. Studies over the last 20 years have revealed a bewildering array of new magnetic phenomena that continue to challenge our understanding of solid-state physics.