  Magnetic topological semimetals present open questions regarding the
interplay of crystal symmetry, magnetism, band topology, and electron
correlations. $LnSb_{x}Te_{2-x-\delta}$ (Ln= lanthanide) is a family of
square-net-derived topological semimetals that allows compositional control of
band filling, and access to different topological states via an evolving charge
density wave (CDW) distortion. Previously studied Gd and Ce members containing
a CDW have shown complex magnetic phase diagrams, which implied that spins
localized on Ln interact with the CDW, but to this date, no magnetic structures
have been solved within the CDW regime of this family of compounds. Here, we
report on the interplay of the CDW with magnetism in $NdSb_{x}Te_{2-x-\delta}$,
by comparing the undistorted square net member $NdSb_{0.94}Te_{0.92}$ with the
CDW-distorted phase $NdSb_{0.48}Te_{1.37}$, via single-crystal x-ray
diffraction, magnetometry, heat capacity, and neutron powder diffraction.
$NdSb_{0.94}Te_{0.92}$ is a collinear antiferromagnet with $T_N$ $\sim$ 2.7 K,
where spins align antiparallel to each other, but parallel to the square net of
the nuclear structure. $NdSb_{0.48}Te_{1.37}$ exhibits a nearly five-fold
modulated CDW ($q_{CDW}=0.18b^*$), isostructural to other
$LnSb_{x}Te_{2-x-\delta}$ at similar x. $NdSb_{0.48}Te_{1.37}$ displays more
complex magnetism with $T_N = 2.3 K$, additional metamagnetic transitions, and
an elliptical cycloid magnetic structure with $q_{mag}=-0.41b^*$.The magnitudes
of $q_{CDW}$ and $q_{mag}$ exhibit a integer relationship,
$1+2q_{mag}=q_{CDW}$, implying a coupling between the CDW and magnetic
structure. Given that the CDW is localized within the nonmagnetic distorted
square net, we propose that conduction electrons "template" the spin modulation
via the Ruderman-Kittel-Kasuya-Yosida interaction.
