  The nucleation in Ising ferromagnet has been studied by Monte Carlo
simulation. Here, the magnetic field is spreading over the space in time. The
nucleation time is observed to increase as compared to that in the case of
static field. The clusters of negative spins is observed to grow from the
center. The growth of effective magnetisation is studied with temperature and
the strength of spreading magnetic field. The ratio of nucleation time and
effective time is also studied with strength of spreading magnetic field. The
effective time would introduce itself as a new scale of time in the case of
nucleation by spatially spreading magnetic field. The effective time and the
nucleation time both are observed to decrease as a power law fashion with the
rate factor of spreading magnetic field.
