Probing Local Structure and Magnetic Order in Low-Dimensional Fe_xNbCh₂ Magnetic Intercalation Compounds

Two-dimensional (2D) transition metal dichalcogenides (TMDs) intercalated with magnetic ions represent a promising class of emergent quantum materials for ultralow-power device applications based on the manipulation of electron spins. The ability to tune the magnetic properties of these compounds based on the choice of host lattice, intercalant, and relative stoichiometry offers a versatile platform for designing 2D magnetic materials, which would otherwise be difficult to access via direct exfoliation of bulk analogues. Recent work from our lab has shown that iron-intercalated tantalum disulfide (Fe_xTaS₂) exhibits long-range ferromagnetic order down to the bilayer limit, due to strong out-of-plane, magnetocrystalline anisotropy (MCA), showcasing the promise of this methodology to engineer non-trivial, low-dimensional magnetic systems. While this approach offers a high degree of modularity, the materials phase space remains largely unexplored—and corresponding experimental demonstration of spin ordering in other low-dimensional compositions remains unknown. Here, we leverage this topotactic intercalation process to synthesize few-layer, iron-intercalated niobium diselenide (Fe_xNbSe₂) and probe the resultant magnetotransport behavior, in the pursuit of electrically addressable, antiferromagnetic ground states akin to this family of iron-intercalated niobium-based dichalcogenides. We utilize a suite of confocal Raman spectroscopy and electron microscopy-based imaging techniques to detect intercalant superlattice formation and survey the local atomic structure, as the distribution of spin-bearing ions in these compounds underpins the character and robustness of long-range spin order. These findings will bolster the capacity to engineer more complex heterostructures and magnetointerfaces within this auspicious family of designer magnetic materials.