MAGNETIC PENETRATION DEPTH AND FLUX DYNAMICS IN SINGLE-CRYSTAL BI2SR2CACU2O8+DELTA

The muon-spin-relaxation technique has been used to study vortex dynamics in single-phase superconducting single crystals of Bi2Sr2CaCu2O8+delta (T(c) almost-equal-to 90 K). The data indicate motional narrowing of the internal field distribution due to vortex motion (on a time scale comparable to the muon lifetime). A field-dependent lattice transition is also observed at T(x) approximately 30 K, as evidenced by the onset of an asymmetric line shape below T(x). Narrowing arising from disordering of the vortices along [001] is also discussed with reference to its effect on the measured penetration depth.