Symmetry Defined Antiferromagnetic Groundstates Coexisting in Co_xNbSe₂

Transition metal dichalcogenides (TMDs) intercalated with 3d-metals exhibit many electronic and magnetic properties, driven by interactions between the host lattice and the intercalated ions. In cobalt intercalated 2H-NbSe₂, the interplay between crystal symmetry and cobalt site occupation leads to two distinct magnetic phases. The system favors a high-temperature magnetic phase at lower cobalt concentrations, while a second, lower-temperature phase emerges at higher concentrations. Our investigation reveals the coexistence of these phases within a superlattice structure, with magnetic transitions linked to different cobalt concentrations. We use bulk property measurements to confirm the presence of these phases, and neutron diffraction techniques to determine the associated magnetic structures.