RF FIELD PENETRATION INTO A BI2SR2CACU2O8 SINGLE-CRYSTAL IN THE MIXED-STATE

The magnetic-field dependence of the effective RF field penetration de pth of a Bi2Sr2CaCu2O8 single crystal has been measured in the mixed s tate under magnetic fields H up to 5T. A crossover from the pinning do minated region at low fields to the dissipative region at high fields has been clearly observed in the intermediate temperature range 0.5 < T/T-c < 0.75. In the pinning dominated region, the field dependence of the elastic pinning force constant (Labusch parameter (alpha(p)) has been estimated to be alpha p proportional to H-1.5 This behavior is si milar to that of conventional superconductors.