BIFURCATION AND MULTIFRACTAL VIBRATION IN DYNAMICS OF A HIGH-T-C SUPERCONDUCTING LEVITATION-SYSTEM

The vibration of a permanent magnet levitated upon a high-T-c supercon ductor shows chaotic motion under external disturbances, The dynamics depends on the nonlinear force-displacement relation between the perma nent magnet and the superconductor, which is related to the magnetic c haracteristics of the superconductor. In the system two typical routes to chaotic motion are found, from the period doubling sequences and f rom the bifurcation of quasi-periodic vibrations. Especially in the la tter route, multifractality appears in the critical state of chaotic m otion that is found in the case of a dissipative system. In this paper , the multifractal vibration of a high-T-c superconducting levitation system is experimentally discussed by estimating the singular point sp ectrum. (C) 1997 Elsevier Science B.V.