In zero field below the superconducting transition $T_{c}$ the linear resistivity disappears, instead, the nonlinear current-voltage characteristics appear. In a picture of vortex dynamics, the nonlinear dissipation is described by the motion of vortices and antivortices, whereas in actual systems heating effects are important at temperatures near $T_{c}$. Here we study the thick amorphous Mo$_x$Si$_{1-x}$ films with the Corbino-disk contacts, in which the vortices (and antivortices) are confined and rotated around the center of the sample, and ``heat sources" are nonuniformly distributed in the radial direction. We have observed unusual large voltage pulses that oscillate almost periodically under the constant radial current in the nonlinear regime just below $T_{c}$. The results indicate the existence of the two metastable states, low- and high-resistive states, and the dynamic transition between them. We suggest that the vortex dynamics and thermal properties are important to understand the phenomena.
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