Precession of spinning magnets levitated over high-temperature superconductors

Both the experimental and theoretical aspects of the precession of a magnet over both a melt-processed and sintered high-temperature superconductor are explored. The freely levitated magnet is spun to high frequencies to obtain a large angular momentum, and tilted using a second magnet. The levitated magnet slowly precesses about a position at least close to the center of mass of the magnet, and the tilt angle decays back to the original orientation. A simple torque equation is used to obtain the applied torque from the measured rate of change of the tilt angle and the precession angle. We discuss how to relate the torques to the moments in the superconductor. (C) 1998 Elsevier science B.V.