  We investigate the structure, chemical bonding, electronic properties, and
magnetic behavior of a three-dimensional graphitic network in aba and aaa
stacking with intercalated transition metal atoms (Mn, Fe, Co, Ni, and Cu).
Using density functional theory, we find induced spin-polarization of the C
atoms both when the graphene sheets are aba stacked (forming graphite) and aaa
stacked (resembling bi-layer graphene). The magnetic moment induced by Mn, Fe,
and Co turns out to vary from 1.38 {\mu}B to 4.10 {\mu}B, whereas intercalation
of Ni and Cu does not lead to a magnetic state. The selective induction of
spin-polarization can be utilized in spintronic and nanoelectronic
applications.
