  Transition metal-pnictide compounds have received attention for their
tendency to combine magnetism and unconventional superconductivity. Binary CoAs
lies on the border of paramagnetism and the more complex behavior seen in
isostructural CrAs, MnP, FeAs, and FeP. Here we report the properties of CoAs
single crystals grown with two distinct techniques along with density
functional theory calculations of its electronic structure and magnetic ground
state. While all indications are that CoAs is paramagnetic, both experiment and
theory suggest proximity to a ferromagnetic instability. Quantum oscillations
are seen in torque measurements up to 31.5~T, and support the calculated
paramagnetic Fermiology.
