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Superconductors may be considered perfect diamagnets, and completely expel magnetic fields due to the Meissner effect when the superconductivity initially forms; thus superconducting levitation can be considered a particular instance of diamagnetic levitation. In a type-II superconductor, the levitation of the magnet is further stabilized due ...
The placement and subsequent levitation of a magnet above an already superconducting material does not demonstrate the Meissner effect, while an initially stationary magnet later being repelled by a superconductor as it is cooled below its critical temperature does.
A high-temperature superconductor levitating above a magnet. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (Meissner effect). This current effectively forms an electromagnet that repels the magnet.
Transition from ordinary conductivity (left) to superconductivity (right). At the transition, the superconductor expels the magnetic field and then acts as a perfect diamagnet. Superconductors may be considered perfect diamagnets (χ v = −1), because they expel all magnetic fields (except in a thin surface layer) due to the Meissner effect. [7]
Diamagnetic levitation of a live frog. Scientists have levitated frogs, [8] grasshoppers, and mice by means of powerful electromagnets utilizing superconductors, producing diamagnetic repulsion of body water. The mice acted confused at first, but adapted to the levitation after approximately four hours, suffering no immediate ill effects. [9] [10]
The wire or tape itself may be made of tiny filaments (about 20 micrometres thick) of superconductor in a copper matrix. The copper is needed to add mechanical stability, and to provide a low resistance path for the large currents in case the temperature rises above T c or the current rises above I c and superconductivity is
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Superdiamagnetism established that the superconductivity of a material was a stage of phase transition. Superconducting magnetic levitation is due to superdiamagnetism, which repels a permanent magnet which approaches the superconductor, and flux pinning, which prevents the magnet floating away. Superdiamagnetism is a feature of superconductivity.