Two-Dimensional Fluctuations Close to the Zero-Field Transition of Bi₂Sr₂CaCu₂O₈

الأصل · EN

The ac-conductivity along the CuO₂-layers of epitaxial films and single crystals of thicknesses 0.2μm≤ Lz ≤130μm reveals clear signatures for 2D-ordering. In particular, at Tc the screening length assumes the universal value LzΛₜc/2νₛ predicted by the Kosterlitz-Thouless theory, which indicates that binding of long vortex strings nucleates long-range superconductivity in the present samples containing up to 10⁵ CuO₂-layers. Several details of the order-parameter dynamics remain unexplained.