MAGNETIC DISSIPATION IN HIGH-TC SUPERCONDUCTORS - EVIDENCE FOR A VORTEX-GLASS-TO-VORTEX-LIQUID TRANSITION

The experimental behaviors of the resistivity as a function of both magnetic field, rho(T)(H), and temperature, rho(H)(T), in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O high-quality samples, are interpreted by means of a phenomenological theory based on two hypotheses: (i) the irreversibility line at zero frequency is the glass-to-liquid-vortex transition, (ii) the dissipation mechanism is that found by Ambegaokar and Halperin and applied by Tinkham to high-T(c) superconductors. The results of the fits performed on the whole range of resistivity variation (five decades) give strong support to the glass model