2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19912Critical fluctuations above $T_c$ are studied in the microwave complex conductivity of BSCCO-2212, BSCCO-2223, and YBCO thin films. The analysis of the experimental data yields the temperature dependences of the reduced coherence length $ξ(T)/ξ_0$. Two critical regimes are observed, having the static critical exponent $ν=1$ close to $T_c$, and a crosover to $ν=2/3$ at higher temperatures. In more anisotropic superconductors the reduced coherence lengths are larger, and the critical states extend to higher temperatures.4 pages, 3 figuresSuperconductivitytext