  In this Chapter we review our latest results on magnetic (AC susceptibility)
and transport (resistivity) properties of Pr1.85Ce0.15CuO4 (PCCO) and
Sm1.85Ce0.15CuO4 (SCCO) thin films grown by pulsed laser deposition technique.
Three main topics of our studies will be covered. We start with a thorough
discussion of the pairing symmetry mechanisms in optimally-doped SCCO thin
films based on the extracted with high accuracy temperature profiles of
penetration depth. In particular, we found that above and below a crossover
temperature T*=0.22T_C, our films are best-fitted by a linear and quadratic
dependencies, respectively, with physically reasonable values of d-wave node
gap parameter and paramagnetic impurity scattering rate. Our next topic is
related to the flux distribution in our films. More precisely, we present a
comparative study on their pinning ability at low magnetic fields extracted
from their AC susceptibilities. Depending on the level of homogeneity of our
films, two different types of the irreversibility line have been found. The
obtained results are described via the critical-state model taking into account
the low-field grain-boundary pinning. And finally, we demonstrate our recent
results on the normal state temperature behavior of resistivity R(T) for the
high-quality optimally-doped SCCO thin films. In addition to the expected
contributions from the electron-phonon and electron-electron scattering
processes, we also observed an unusual step-like behavior of R(T) around T=87K
which we attributed the to the manifestation of thermal excitations due to spin
fluctuations induced by Sm3+ moments through Cu2+-Sm3+ interaction.
