One of the most important properties of a class of materials called "superconductors" is that magnetic fields cannot penetrate into the material. This means they can be used to levitate magnets and even to build magnetic levitation trains this is currently being done in Japanwhich float 10mm above the tracks on a magnetic field. Some examples of superconductors that people have know about for over 90 years are Mercury, Tin, and Lead.
Superconductivity is characterized both by perfect conductivity zero resistance and by the expulsion of magnetic fields the Meissner effect. Changes in either temperature or magnetic field can cause the phase transition between normal and superconducting states. The highest temperature under which the superconducting state is seen is known as the critical temperature.
Such a distribution of magnetic field lines is expected for a type-II superconductor with flux pinning, i. Magnetic field is partly excluded from the superconductor. Hence, the same repulsion as between a magnet and a diamagnetic.
Below a certain temperature, materials enter a superconducting state and offer no resistance to the passage of electrical current. Inwhile studying the properties of matter at very low temperature, the Dutch physicist Heike Kamerlingh Onnes and his team discovered that the electrical resistance of mercury goes to zero below 4. This was the very first observation of the phenomenon of superconductivity.
Superconductivity conforms to a quantum, thermal, and electrodynamic set of physical phenomena of great interest by themselves. They have, also, the potential to be one clean energy source that technology is looking for. Superconductors do not allow static magnetic fields to penetrate them below a critical field, that is, Meissner effect.
Maluf and F. We have shown that the Paramagnetic Meissner Effect PME is directly associated with pinning, and not necessarily related to the presence of p -junctions. Through the study of the magnetic properties of two-dimensional Josephson junction arrays 2D-JJA in the present work we show that, among the systems exhibiting PME, only those with suffciently low dissipation and high capacitance will show dynamics reentrance.
The Meissner effect or Meissner—Ochsenfeld effect is the expulsion of a magnetic field from a superconductor during its transition to the superconducting state. The German physicists Walther Meissner and Robert Ochsenfeld  discovered this phenomenon in by measuring the magnetic field distribution outside superconducting tin and lead samples. They detected this effect only indirectly because the magnetic flux is conserved by a superconductor: when the interior field decreases, the exterior field increases.
Depending on how you slice the pie, there are either many kinds of superconductors or only two. From the perspective of how they behave in magnetic fields, however, scientists commonly classify them into two groups. A Type I superconductor is usually made of a pure metal. When cooled below its critical temperature, such a material exhibits zero electrical resistivity and displays perfect diamagnetismmeaning magnetic fields cannot penetrate it while it is in the superconducting state.