© Wikimedia Commons, GNU Free Documentation License, Version 1.2. Author: Mai-Linh Doan, 13 October 2007.
The levitation is produced by the diamagnetic currents induced in the superconductor by the magnetic field produced by the magnet. Prior to 1986, demonstrations of this effect required liquid helium to cool the superconducting material below its superconducting transition temperature, TC. With the advent of the cuprate superconductors, such as YBCO, whose TC exceeds 90 K, a demonstration now requires only a YBCO sample and liquid nitrogen, both of which are inexpensive and readily available. Magnetically levitated trains that float above a track are now feasible, and a google search will turn up excellent educational films about these. (Unit: 8)