  We report magneto-transport measurements on a superconducting
molybdenum-germanium (MoGe) film of thickness $d$=50 nm in parallel magnetic
fields and show evidence of a transition from a Meissner state to a resistive
state of spontaneous perpendicular vortices generated by thermal fluctuations
above a certain temperature $T>T_v(B)$. Here $T_v$ appears to match the vortex
core explosion condition $d\approx 4.4\xi(T_v)$, where $\xi$ is the coherence
length. For $T>T_v$, we observed that a nonlinear current-voltage ($IV$)
response (Ohmic at low currents and the power law $V\propto I^\beta$ at higher
$I$) is exponentially dependent on $B^2$. We propose a model in which the
resistive state at $T>T_v$ is due to thermally-activated hopping of spontaneous
perpendicular vortices tuned by the pairbreaking effect of the parallel $B$.
  keywords: vortex, vortices, fluxon, flux lattice, mixed state, lower critical
field
