superconductivity and magnetism in Pr-rich alloys*

The Pr-rich end of the alloy series Pr_1−xNd_xOs4Sb₁₂ has been studied using muon spin rotation and relaxation. The end compound PrOs₄Sb₁₂ is an unconventional heavy-fermion superconductor, which exhibits a spontaneous magnetic field in the superconducting phase associated with broken time-reversal symmetry. No spontaneous field is observed in the Nd-doped alloys for x ≥ 0.05. The superfluid density is insensitive to Nd concentration, and no Nd³⁺ static magnetism is found down to the lowest temperatures of measurement. Together with the slow suppression of the superconducting transition temperature with Nd doping, these results suggest anomalously weak coupling between Nd spins and conduction-band states. [1]
[1] P.-C. Ho et al., arXiv:1910.01757