An
ideally hard superconductor is a
type II superconductor material with an infinite
pinning force (or
critical current density). In the external magnetic field it behaves like an ideal
diamagnet if the field is switched on when the material is in the superconducting state, so-called "zero field cooled" (ZFC) regime. In the field cooled (FC) regime, the ideally hard superconductor screens perfectly the change of the magnetic field rather than the magnetic field itself. The ideally hard superconductor is a good approximation for the melt-textured
high temperature superconductors (HTSC) used in large scale HTSC applications such as
flywheels, HTSC bearings, HTSC motors, etc.
References