Chapter 1 - Spin Glasses

Spin glass, a class of random magnets with competing ferromagnetic and antiferromagnetic interactions, has extensively been studied both experimentally and theoretically for more than 40 years now. Spin glasses are characterized by frustration and randomness, and often give rise to novel magnetic properties, unique ordering behaviors, and fascinating off-equilibrium dynamics. Not just limited to magnets, spin glass-like behaviors are observed quite ubiquitously in a wide variety of materials in nature, such as in multiferroics, relaxors, strongly correlated electrons, and superconductors. Indeed, the spin glass research has contributed in developing novel concepts such as “many pure states,” “replica-symmetry breaking,” “chirality and chiral glass,” “aging,” “memory and rejuvenation,” “off-equilibrium fluctuation–dissipation theorem,” etc. We review these hot research activities on spin glasses over these 40 years from a unified perspective.