Correlation of Frictional Losses of Spinning Levitated Magnets with AC Susceptibility in High Temperature Superconductors

Measurements of both the ac magnetic susceptibility in melt processed and film Y–Ba–Cu–O and frictional losses of spinning permanent magnets levitated above Y–Ba–Cu–O are presented. A direct correlation is observed only when large susceptibility samples are studied indicative of the importance of grain boundary loss mechanisms. The increasing loss per revolution with increasing frequency for a spinning permanent magnet is explored.