  While several magnetic topological semimetals have been discovered in recent
years, their band structures are far from ideal, often obscured by trivial
bands at the Fermi energy. Square-net materials with clean, linearly dispersing
bands show potential to circumvent this issue. CeSbTe, a square-net material,
features multiple magnetic field-controllable topological phases. Here, it is
shown that in this material, even higher degrees of tunability can be achieved
by changing the electron count at the square-net motif. Increased electron
filling results in structural distortion and formation of charge density waves
(CDWs). The modulation wave-vector evolves continuously leading to a region of
multiple discrete CDWs and a corresponding complex "Devil's staircase" magnetic
ground state. A series of fractionally quantized magnetization plateaus are
observed, which implies direct coupling between CDW and a collective
spin-excitation. It is further shown that the CDW creates a robust idealized
non-symmorphic Dirac semimetal, thus providing access to topological systems
with rich magnetism.
