DETECTION OF VORTEX MOTION IN HIGH-T(C) SUPERCONDUCTOR BY N-S POINT-CONTACT

A N-S point contact (platinum tip-ab-plane of a Bi2Sr2CaCu2O8 single c rystal) has been used for the first time to detect the vortex motion i n a high-T(c) superconductor. The sweep of an external magnetic field led to the appearance of voltage pulses on the contact (when a constan t current was passed through the contact), which were associated with the passage of individual vortices through the contact. An abrupt decr ease of the pulse amplitude with increasing temperature has also been observed. This fact may be explained by thermal fluctuations of the vo rtex lattice.