Szczegóły publikacji

The diversity of magnetic orders that appear in layered magnetic materials is of great interest from the fundamental point of view and for applications. In particular, the magnetic sublayers, introduced by intercalation into van der Waals gaps of the host transition-metal dichalcogenide (TMD), are known to produce various magnetic states, with some being tunable by pressure and doping. The magnetic sublayers and their magnetic ordering strongly modify the electronic coupling between layers of the host compound. Understanding the roots of this variability, starting from the underlying electronic structure, is a significant challenge. Here we employ the angle-resolved photoelectron spectroscopy at various photon energies, the ab initio electronic structure calculations, and modeling to address the particular case of Ni-intercalate, Ni1/3NbS2. We find that the bands around the Fermi level bear the signature of a strong yet unusual hybridization between NbS2 conduction band states and the Ni 3d orbitals. The hybridization between metallic NbS2 layers is almost entirely suppressed in the central part of the Brillouin zone, including the part of the Fermi surface around the Γ point. Simultaneously, it gets very pronounced towards the zone edges. It is shown that this behavior is the consequence of the rather exceptional, symmetry imposed, spatially strongly varying, zero total hybridization between relevant Ni magnetic orbitals and the neighboring Nb orbitals that constitute the metallic bands. We also report the presence of the so-called β feature, discovered only recently in two other magnetic intercalates with very different magnetic orderings. In Ni1/3NbS2, the feature shows only at particular photon energies, indicating its bulk origin. Common to prior observations, it appears as a series of very shallow electron pockets at the Fermi level, positioned along the edge of the Brillouin zone. Unforeseen by ab initio electronic calculations, and its origin still unresolved, the feature appears to be a robust consequence of the intercalation of 2H-NbS2 with magnetic ions.