Metal-Insulator Transition in Disordered Solids

The beauty and rarity of crystals has fascinated mankind for thousands of years. Most solids, however, are either disordered by imperfections or they lack a periodic lattice of atoms at all: they are amorphous. The periodicity of a crystal simplifies the theoretical understanding of its physical properties. At low concentrations the effect of imperfections can often be thought of as a superposition of single imperfections. At high concentrations these imperfections may interfere and lead to new cooperative phenomena. Statistical mechanics and solid state physics have gained many insights into strongly disordered systems during the last decade. New structures and fascinating symmetries appear on a deeper theoretical level. One of the phenomena where progress has been made is the metal-insulator transition induced by disorder.