MEASUREMENTS OF TRANSPORT PROPERTIES AND NOISE POWER SPECTRAL DENSITIES FOR Bi2Sr2Ca1Cu2Ox SINGLE CRYSTALS

We measured the current-voltage characteristics of Bi2Sr2Ca1Cu2Ox single crystals along the a-b plane and observed the behavior of Kosterlitz-Thouless(K-T) transition. Noise power spectral density, S,(f) near K-T transition temperature was studied in detail by changing the temperature, magnetic field, and current. We found that SA at temperatures above a K-T transition temperature Trr shows a 1/f behavior regardless of the external magnetic field. However near Tu, the S,(f) deviates markedly from the 1/f behavior for the experimental frequency range. We believe that the anomalous variation of frequency dependence near Tx,. originates from the fluctuation effect of the vortex-antivortex pairs, i.e. their annihilation-creation fluctuations.