Long-range magnetic order in the magnetodielectric regime of Ce₂O₃

The metastable sesquioxide, Ce₂O₃, has been a material of intense interest in recent years due to reports of an anomalous giant magnetodielectric effect and the emergence of vibronic modes below a putative antiferromagnetic transition at T_N = 6.2K. The claim of long-range magnetic order in this material is based on heat capacity and temperature-dependent susceptibility measurements. Curiously, three previous neutron diffraction studies were unable to distinguish any magnetic Bragg peaks, casting doubt on the nature of the low temperature state. To address this point, we undertook a comprehensive study of polycrystalline Ce₂O₃ using neutron diffraction, triple-axis and time-of-flight inelastic neutron scattering, and muon spin rotation. I will report evidence of magnetic order in Ce₂O₃ and discuss these results in light of our current understanding of the underlying physics.