  Co$_{1/3}$NbS$_2$ is the magnetic intercalate of 2H-NbS$_2$ where electronic
itinerant and magnetic properties strongly influence each other throughout the
phase diagram. Here we report the first angle-resolved photoelectron
spectroscopy (ARPES) study in Co$_{1/3}$NbS$_2$. The observed electronic
structure seemingly resembles the one of the parent material 2H-NbS$_2$, with
the shift in Fermi energy of 0.5 eV accounting for the charge transfer of
approximately two electrons from each Co ion into the NbS$_2$ layers. However,
we observe significant departures from the 2H-NbS$_2$ rigid band picture:
Entirely unrelated to the 2H-NbS$_2$ electronic structure, a shallow electronic
band is found crossing the Fermi level near the boundary of the first Brillouin
zone of the superstructure imposed by the intercalation. The evolution of the
experimental spectra upon varying the incident photon energy suggests the Co
origin of this band. Second, the Nb bonding band, found deeply submerged below
the Fermi level at the $\Gamma$ point, indicates the interlayer-hybridization
being very much amplified by intercalation, with Co magnetic ions probably
acting as covalent bridges between NbS$_2$ layers. The strong hybridization
between conducting and magnetic degrees of freedom suggests dealing with
strongly correlated electron system where the interlayer coupling plays an
exquisite role.
