In solid state physics, this most often refers to the vortex pinning, the pinning of the magnetic vortices (magnetic flux quanta, Abrikosov vortices) by different kinds of the defects in a type II superconductor.
Important quantities are the individual maximal pinning force, which defines the depinning of a single vortex, and an average pinning force, which defines the depinning of the correlated vortex structures and can be associated with the critical current density (the maximal density of non-dissipative current).
This phase diagram is especially rich for high temperature superconductors (HTSC) where the thermo-activation processes are essential.
It is also assumed that particles are spherical and the particle-matrix interface is incoherent.
When a moving grain boundary meets a particle at an angle