Ferroelastic Materials

Large elastic nonlinearities can lead to elastic hysteresis behavior, which defines ferroelasticity in analogy to its sister ferroics: ferromagnetism and ferroelectricity. Ferroelasticity is the most common nonlinear effect in natural materials and plays a major role in the mineralogical behavior of the Earth's crust and mantle. It produces interfacial twin walls that act as sinks and sources for defects and that show localized effects such as superconducting twin boundaries and ferroelectricity, even when such effects do not exist in the bulk. The movement of twin walls under elastic forcing is creep-like, with some superimposed jerks due to pinning and unpinning by defects and jamming by other twin boundaries. This review applies Landau theory and discusses some aspects of the emerging field of domain boundary engineering.