  Metallic ferromagnets with strongly interacting electrons often exhibit
remarkable electronic phases such as ferromagnetic superconductivity, complex
spin textures, and nontrivial topology. In this report, we discuss the
synthesis of a layered magnetic metal NiTa$_4$Se$_8$ (or Ni$_{1/4}$TaSe$_{2}$)
with a Curie temperature of 58 Kelvin. Magnetization data and \textit{ab
initio} calculations indicate that the nickel atoms host uniaxial ferromagnetic
order of about 0.7$\mu_{B}$ per atom, while an even smaller moment is generated
in the itinerant tantalum conduction electrons. Strong correlations are evident
in flat bands near the Fermi level, a high heat capacity coefficient, and a
high Kadowaki-Woods ratio. When the system is diluted of magnetic ions, the
samples become superconducting below about 2 Kelvin. Remarkably, electron and
hole Fermi surfaces are associated with opposite spin polarization. We discuss
the implications of this feature on the superconductivity that emerges near
itinerant ferromagnetism in this material, including the possibility of
spin-polarized superconductivity.
