Large vortex-density fluctuations induced by current in the Corbino-disk

Abstract: We have studied the vortex dynamics driven by the constant current I in the Meissner phase of a thick amorphous Mo x Si1−x film with the Corbino-disk contact geometry. In the certain I region we have observed unusual large voltage pulses that oscillate almost periodically with a period t 0 larger than ∼15 s and with the pulse width t w in the range 5–10s. With increasing I, t 0 initially decreases and then increases. Over the whole I region where the oscillation of V(t) is observed, both t 0 and t w are much longer than the characteristic time for free vortices to rotate in the circles. At high I a small peak(s) or cusp-like structure exceeding the normal-state voltage appears on the top (plateau) region of the pulses. These results indicate that the observed voltage pulses originate from large vortex-density fluctuations of moving vortices. [Copyright &y& Elsevier]