Algebraic decay of fluxoid-dynamics in the BSCCO high-Tc superconductor

From measurements of the complex ac-susceptibility between 3 Hz and 2 MHz on a dense ceramic cylinder in a field of 1 tesla the complex frequency-dependent penetration depth λac(ω) is evaluated. A novel algebraic law, λ2ac(ω, T)∼(iωτ0)−β(T) is obtained, the exponent of which drops discontinuously to low values (β⩽0.2) at the glass transition Tg=20 K and increases linearly to the conventional value β=1 at Tl=70 K. Above Tl the dynamics indicates a vortex liquid (β=1) defining an intrinsic transition, which unlike the irreversibility line does not depend on external parameters like sample radius and observation time.