Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-481-C8-484
Ultrasonic Studies of Textured Superconducting Bi2Sr2CaCu2O8+y in Magnetic FieldsQ. Wang1, D.P. Almond1, G.A. Saunders1, S.B. Palmer2, C.M. Lim2 and K.C. Goretta3
1 Schools of Physics and Materials Science, University of Bath, Bath, BA2 7AY, U.K.
2 Department of Physics, University of Warwick, Coventry, CV4 7AL, U.K.
3 Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439, U.S.A.
Measurements have been made of ultrasonic shear wave attenuation and sound velocity in highly textured polycrystalline samples of Bi2Sr2CaCu2O8+y in magnetic fields up to 9 telsa and at temperatures down to 4.2 K. Magnetic field dependent attenuation peaks and velocity enhancements were found that are in good agreement with theoretical predictions based on the assumptions of the thermally assisted flux flow model of the mixed state. A pinning activation energy of ≈ 160K was deduced from the ultrasonic data. Pinning energy showed little evidence of dependence upon magnetic field magnitude or orientation. The flux-line lattice was found to be pinned fully at lowest temperatures.
© EDP Sciences 1996