Superconductor magnet demonstration. Neodymium magnet (top) being used to demonstrate the properties of a superconducting magnet (bottom) that has been cooled to low temperatures using liquid nitrogen. The superconductor (in the styrofoam) is a YBCO superconductor, a ceramic alloy of oxides of yttrium, barium and copper. This material loses its electrical resistance at minus 184 degrees Celsius. Liquid nitrogen cools it to minus 196 degrees Celsius. As well as becoming a superconductor at these temperatures, a phenomenon where magnetic fields are ejected or constrained to the superconductor's surface occurs, leading to the repulsion and levitation effects seen here.