Abstract
Flux pinning interaction originates from the variation in the energy of a flux line during its displacement across inhomogeneous regions called pinning centers such as normal precipitates or grain boundaries. The flux pinning mechanism is classified according to the dominant energy involved in the interaction. Normal precipitates and grain boundaries work as strong pinning centers through a condensation energy interaction. The field-induced pinning resulting from a weak superconducting region is also classified in the condensation energy interaction. Magnetic interaction and kinetic interaction are also introduced. The pinning mechanism of artificially introduced Nb into Nb-Ti is considered to be a kinetic energy interaction.
