The materials that show a complex phenomenon, the superconductivity, are called superconductors. Below a temperature, named “transition temperature”, the superconductors stop opposing the electrical current flow and expel the magnetic fields that are inside (Meissner effect). The transition temperature depends on the material nature, on the magnetic fields presence and on the current density that is flowing through the material.

MIT researchers have discovered that some high temperature superconductors show variations at atomic scale, variations totally unknown in a property named Fermi surface (that is a measurement of the distribution of electrons in a material). Probably this is the opportunity for the researchers to understand finally why, in a large new class of materials, the interactions among the electrons (generally they can be ignored due to their weakness!) control the material physics.

Till now physicists believed that the Fermi surface was uniform across any material, but in this superconductors new class even the electrons separated just by an atom distance are very different! MIT researchers are not alone in this job that could keep other surprises: the researchers from Nagoya University (Japan) and from Brookhaven National Laboratory are also giving their contribute.

Source: http://web.mit.edu/newsoffice/2009/superconduct-0127.html