Spin micromechanics in the physics of plasticity

The effect of the spin states of structural defects on the mechanical properties of a crystal is the subject of spin micromechanics — a discipline that emerged at the junction of solid state physics, spin chemistry, and plasticity physics. The main reason for considering the electron spin when discussing elementary processes in plastically deformed crystals is the solid experimental evidence of recent years that the multiplicity of excited short-lived defect pairs affects the way in which dislocations (plastic deformation carriers) move in various nonmagnetically ordered crystals. Because the contribution of defect spin states to mechanical properties can basically be found from magnetic field effects on plasticity, the systematization and analysis of recent experimental data on such effects are given the main attention in this review. In interpreting these effects, analogies between the elementary events of a dislocation overcoming an obstacle and the earlier studied spin-dependent processes (charge transfer, light emission, intermolecular chemical bond formation) are employed.