Magnetic Substitution in j=3/2 Superconductor YPtBi

The superconducting state of half-Heusler topological semimetal YPtBi promises exciting possibilities. Due to the strong spin-orbit coupling leading to band inversion and j=3/2 quasiparticles, Cooper pairs may support quintet (j=2) and septet (j=3) pairing states, beyond the singlet (j=0) and triplet (j=1). Penetration depth experiments have established nodal superconductivity in YPtBi. Here, we present a study of the effect of magnetic-ion Nd substitution on the superconductivity of YPtBi in Y1−xNdxPtBi samples. Scattering in nodal superconductors can destroy the superconducting gap. Magnetic scattering is time reversal symmetry breaking and can destroy even non-nodal superconducting gaps. Our experiments show that, despite magnetic scattering due to the Nd substitution (up to x = 0.48), the superconductivity in YPtBi survives with less than 5% reduction in the transition temperature in multiple samples. These surprising results indicate that the nodal superconducting state in YPtBi is robust under magnetic scattering and suggest an exotic nature of superconductivity in YPtBi. Contemporary proposals for a superconducting state for YPtBi discuss more than one pairing channel in the form ∆(k) = F1(k) + iF2(k) which may offer protection against magnetic pair-breaking, as observed in our experiments.