Characteristics of superconductors: (1) zero electrical resistance, (2) rejection of magnetic flux.

http://www.superconductors.org/

• Type I superconductor remains superconducting at low applied H fields and low temperature T.
• Type II superconductor has a mixed state at medium H fields where metallic vortices are formed, with the rest of the material being a superconductor.
  • This results in some residual resistance arising from the movement of the vortices due to the Lorentz force.

Some keywords:

• BCS theory - need knowledge in condensed matter
• Superconducting tunneling