Interaction between a permanent magnet and an HTS trapped field magnet

High temperature superconductor trapped field magnets were made out of disks of melt-textured YBa/sub 2/Cu/sub 3/O/sub 7/ prepared by the seeded directional solidification method. It is shown that the force between the magnet and the HTS trapped field magnet depends on the polarity of the frozen magnetic field and can be positive or negative. The levitation force between a magnet and a trapped field magnet is compared with that between the same magnet and a high temperature superconductor without trapped flux under zero field cooled condition. The stability of a levitation system based on the trapped field magnets has been investigated by studying the amplitude-frequency characteristics of the system where a permanent magnet is attached to a soft cantilever beam and placed above the trapped field magnet.