Search for time-reversal-symmetry-breaking magnetism in PrCuSb₂

Collective magnetism can transform Dirac fermions into Weyl fermions in centrosymmetric topological semimetals. Realizing these magnetic Weyl semimetals is of interest for studying unconventional electronic behavior and for applications in spintronics devices. Isostructural to the anisotropic Dirac superconductor LaCuSb₂, the reported ferromagnet PrCuSb₂ is a natural candidate in searching for time-reversal-symmetry-breaking magnetism in a Dirac material. Using a combination of thermodynamic and neutron diffraction measurements, we show that PrCuSb₂ undergoes a transition into a long-wavelength magnetic state below T = 5 K. The system is easily magnetized with out-of-plane fields and features a hysteresis loop at low temperatures. We highlight models to explain the magnetic structure, and discuss possible connections to electronic properties in this magnetic analog to a Dirac superconductor.