  We study the irreversible growth of magnetic thin films under the influence
of spatially periodic fields by means of extensive Monte Carlo simulations. We
find first-order pseudo-phase transitions that separate a dynamically
disordered phase from a dynamically ordered phase. By analogy with
time-dependent oscillating fields applied to Ising-type models, we
qualitatively associate this dynamic transition with the
localization/delocalization transition of "spatial hysteresis" loops. Depending
on the relative width of the magnetic film, $L$, compared to the wavelength of
the external field, $\lambda$, different transition regimes are observed. For
small systems ($L<\lambda$), the transition is associated with the Standard
Stochastic Resonance regime, while, for large systems ($L>\lambda$), the
transition is driven by Anomalous Stochastic Resonance. The origin of the
latter is identified as due to the emergence of an additional relevant
lengthscale, namely the roughness of the spin domain switching interface. The
distinction between different stochastic resonance regimes is discussed at
length, both qualitatively by means of snapshot configurations, as well as
quantitatively via residence-length and order-parameter probability
distributions.
