The magnetic levitation forces of superconductors is dependent on a cooling method of the superconductors. The method, which cools the superconductors using LN2 in an environment with no external magnetic field, is called zero-field cooling (ZFC). The ZFC superconductors have a perfect diamagnetic state. The superconductors actively push the magnetic field of a magnet. On the other hand, the method, which cools the superconductors using LN2 in a magnetic field environment, is called field cooling (FC). In FC, the magnets are placed above or below the superconductors and the superconductor is cooled using LN2. The FC superconductors capture the magnetic field of the magnets. Therefore, the FC superconductors not only push the magnets by the perfect diamagnetism, but also attract the magnets at the same time. This chapter introduces the cooling method used for the Meissner effect experiment (ZFC) the magnetic flux pinning experiments (FC).
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