Perfect Diamagnetism
Superconductors in the Meissner state exhibit perfect diamagnetism, or superdiamagnetism, meaning that the total magnetic field is very close to zero deep inside them (many penetration depths from the surface). This means that their magnetic susceptibility, = −1. Diamagnetics are defined by the generation of a spontaneous magnetization of a material which directly opposes the direction of an applied field. However, the fundamental origins of diamagnetism in superconductors and normal materials are very different. In normal materials diamagnetism arises as a direct result of the orbital spin of electrons about the nuclei of an atom induced electromagnetically by the application of an applied field. In superconductors the illusion of perfect diamagnetism arises from persistent screening currents which flow to oppose the applied field (the Meissner effect); not solely the orbital spin.
Read more about this topic: Meissner Effect
Famous quotes containing the word perfect:
“One of the main things that interfere with our joy is the belief that if we try hard enough, read the right books, follow the right advice, and buy the right things, we could be perfect parents. If we are good enough as parents, our children will be perfect too.... Unfortunately, what comes from trying to live out this philosophy is not perfect children but worried parents.”
—Lawrence Kutner (20th century)