LONDON-SILSBEE STATE IN MAGNETICALLY TEXTURED DYBA2CU3O7-X - FILAMENTARY PERCOLATION

A highly textured DyBa2Cu3O7-x sample has been grown by melting and cooling in an external magnetic field. V vs. I characteristics have been measured as a function of temperature. The results are interpreted in terms of the so-called London model of current-induced destruction of superconductivity in a filamentary structure. The critical current deduced from these I-V curves shows a linear temperature dependence which is consistent with the so-called Silsbee state, and leads to a Silsbee critical current of ca. .380 mA at T = 0, and corresponds to a 0.5 T thermodynamic critical field. This field is in agreement with the structure deduced from microscopic observation and reveals that the percolation transition starts from a filamentary mechanism for the superconductivity destruction with increasing temperature.