  The superconducting transition temperature $T_{c}$ of multilayers of
electron-doped cuprates, composed of underdoped (or undoped) and overdoped La%
$_{2-x}$Ce$_{x}$CuO$_{4}$ (LCCO) and Pr$_{2-x}$Ce$_{x}$CuO$_{4}$ (PCCO) thin
films, is found to increase significantly with respect to the $T_{c}$ of the
corresponding single-phase films. By investigating the critical current density
of superlattices with different doping levels and layer thicknesses, we find
that the $T_{c}$ enhancement is caused by a redistribution of charge over an
anomalously large distance.
