Single-crystal neutron diffraction study of the heavy-electron superconductor CeNiGe₃

A single-crystal neutron diffraction study was performed on anomalous antiferromagnetic ordering in the heavyelectron superconductor CeNiGe₃. We observed incommensurate magnetic Bragg reflections characterized by the incommensurate propagation vector k₂ = (0; 0:41; 1/2) below the Néel temperature of 5K, but no significant magnetic reflection with the commensurate propagation vector k₁ = (1; 0; 0), at which another magnetic reflection was observed in a previous neutron diffraction study with a polycrystalline sample. From the single-crystal study, we suggest that the magnetic phase of CeNiGe₃ at ambient pressure is characterized only by the incommensurate propagation vector k₂.