High-temperature superconductors
High critical temperature superconductors - Physics and applications

A superconductor is a material that conducts electric current without resistance below a certain "critical" temperature (T_c). Unlike ordinary metals, which are subject to the Joule effect, there is no dissipation of energy when a direct current flows through a superconductor: it is a perfect conductor, and its electrical resistance is zero. When cooled to below T_c in the presence of a magnetic field, the latter is expelled from the material. It is a perfect diamagnetic material, and magnetic induction B is zero in its volume. Perfect conduction and diamagnetism are therefore the two generic properties of a superconductor, which manifest themselves when it is cooled below T_c; it passes from the so-called "normal" phase, where...