when an external magnetic field from the PM is applied to the HTS the flux pinning provides the formation of induction gradients in the superconductor.
Definition of flux pinning in English English dictionary
Flux pinning is the phenomenon that magnetic flux lines do not move (become trapped, or "pinned") in spite of the Lorentz force acting on them inside a current-carrying Type II superconductor. The phenomenon cannot occur in Type I superconductors, since these cannot be penetrated by magnetic fields (Meissner-Ochsenfeld effect). Flux pinning is only possible when there are defects in the crystalline structure of the superconductor (usually resulting from grain boundaries or impurities)