  We report superconductivity and magnetism in a new family of topological
semimetals, the ternary half Heusler compounds $R$PdBi ($R$ : rare earth). In
this series, tuning of the rare earth $f$-electron component allows for
simultaneous control of both lattice density via lanthanide contraction, as
well as the strength of magnetic interaction via de Gennes scaling, allowing
for a unique tuning of both the normal state band inversion strength,
superconducting pairing and magnetically ordered ground states.
Antiferromagnetism with ordering vector (0.5,0.5,0.5) occurs below a Ne\'eel
temperature that scales with de Gennes factor $dG$, while a superconducting
transition is simultaneously linearly suppressed. With superconductivity
appearing in a system with non-centrosymmetric crystallographic symmetry, the
possibility of spin-triplet Cooper pairing with non-trivial topology analogous
to that predicted for the normal state electronic structure provides a unique
and rich opportunity to realize both predicted and new exotic excitations in
topological materials.
