Transition-metal dichalcogenides (TMDs) intercalated
with magnetic
ions serve as a promising materials platform for developing next-generation,
spin-based electronic technologies. In these materials, one can access
a rich magnetic phase space depending on the choice of intercalant,
host lattice, and relative stoichiometry. The distribution of these
intercalant ions across given crystals, however, is less well defined—particularly
away from ideal packing stoichiometries—and a convenient probe
to assess potential longer-range ordering of intercalants is lacking.
Here, we demonstrate that confocal Raman spectroscopy is a powerful
tool for mapping the onset of intercalant superlattice formation in
Fe-intercalated NbSe2(FexNbSe2) for 0.14 ≤x< 0.25. We use single-crystal
X-ray diffraction to confirm the presence of longer-range intercalant
superstructure and employ polarization-, temperature-, and magnetic
field-dependent Raman measurements to examine both the symmetry of
emergent phonon modes in the intercalated material and potential magnetoelastic
coupling. Magnetometry measurements further indicate a correlation
between the onset of magnetic ordering and the relative degree of
intercalant superlattice formation. These results show Raman spectroscopy
to be an expedient, local probe for mapping intercalant ordering in
this class of magnetic materials.