PINNING IN THE FLUX-LINE-CUTTING REGIME OF BI2SR2CA1CU2O8 SINGLE-CRYSTALS AT HIGH-FIELD

Using a low-frequency torsion pendulum we show that in a Bi2Sr2Ca1Cu2O 8 Single crystal the irreversibility line B-irr(T) is frequency depend ent down to 10(-5) Hz in the high-field regime. The activation energy has a logarithmic field dependence, U-0(B)=U1n(B*/B). A microscopic m odel for flux-line-cutting and pancake collision yields quantitative e xpressions for U(0)and for B-irr( T)=B exp(- T/T*), which reproduce t he experimental data very well.