Role of intercalated cobalt in the electronic structure of Co1/3NbS2

Co1/3NbS2 is the magnetic intercalate of 2H-NbS2 where electronic itinerant and magnetic properties strongly influence each other throughout the phase diagram. Here we report the angle-resolved photoelectron spectroscopy (ARPES) study in Co1/3NbS2. In agreement with previous reports, the observed electronic structure seemingly resembles the one of the parent material 2H-NbS2, 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 NbS2 layers. However, in addition, and in contrast to previous reports, we observe significant departures that cannot be explained by the rigid band shift accompanied by minor deformation of bands: First, entirely unrelated to the 2H-NbS2 electronic structure, a shallow electronic band is found crossing the Fermi level near the boundary of the first Brillouin zone of Co1/3NbS2. 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 I' point, indicates that the interlayer hybridization is significantly amplified by intercalation, with Co magnetic ions probably acting as strong covalent bridges between NbS2 layers. The strong hybridization between orbitals that support the itinerant states and the orbitals hosting the local magnetic moments indicates the importance of strong electronic correlations, with the interlayer coupling playing an exquisite role.