Magnetic Properties of High-Temperature Superconductors

Next to zero resistivity, the most attractive property of superconductors is their response to magnetic fields. High-temperature superconductors are classified as type II superconductors, which can be penetrated by magnetic flux lines. When type II superconductors contain pinning centers, they behave like both diamagnetic and ferromagnetic materials, depending on the magnetizing process. Such properties can be used to stably levitate a heavy object or to suspend it in midair. A variety of applications are now under consideration, such as magnetic bearings, flywheels, transportation systems, and magnetic shields. It is also possible to magnetize strongly pinned superconductors, which then behave like permanent magnets.