  Two-dimensional (2D) materials combined with the presence of surface
nearly-free electrons (NFE) have been considered quite interesting platforms to
be exploited for the development of 2D electronic devices. Further
incorporation of foreign elements adds a new degree of freedom to engineer the
electronic as well as the magnetic properties of 2D materials. Here we have
performed an ab-initio study of Ca$_{2}$N, electrenes fully (i.e., both sides)
adsorbed by hydrogen (H/Ca$_{2}$N/H) and fluorine (F/Ca$_{2}$N/F) atoms. The
NFE states are suppressed in these systems, followed by the appearance of a net
magnetic moment localized in the nitrogen atoms intercalated by the
hydrogenated or fluorinated calcium layers. In the sequence, we have proposed
lateral heterostructures combining the H/Ca$_{2}$N/H or F/Ca$_{2}$N/F regions
with pristine Ca$_{2}$N, electrenes [(Ca$_{2}$N)(X/Ca$_{2}$N/X), with X=H or
F]. We found that the magnetic moment of the hydrogenated or fluorinated
regions promotes the emergence of spin-polarized NFE states confined along the
pristine (Ca$_{2}$N) stripes. Further electronic transport calculations reveal
that the (X/Ca$_{2}$N/X) regions act as spin-dependent scattering centers,
spin-filters. We believe that these findings make an important contribution to
the development of spintronic devices based on 2D electrides.
