  The sesquioxide, Ce$_{2}$O$_{3}$, has been a material of intense interest in
recent years due to reports of an anomalous giant magnetodielectric effect and
emergent mixed crystal field-phonon (vibronic) excitations below a putative
antiferromagnetic transition at T$_{N}$ = 6.2 K. The claim of long-range
magnetic order in this material is based on heat capacity and
temperature-dependent susceptibility measurements; however, multiple neutron
diffraction studies have been unable to distinguish any magnetic Bragg peaks.
In this article, we present the results of a comprehensive investigation of the
low-temperature phase in symmetry-broken polycrystalline Ce$_{2}$O$_{3}$ using
a combination of magnetic susceptibility, heat capacity, neutron diffraction,
triple-axis and time-of-flight (TOF) inelastic neutron scattering (INS), and
muon spin rotation ($\mu$SR). Our measurements and subsequent analysis confirm
that the transition at T$_{N}$ can be associated with the ordering of moments
on the Ce$^{3+}$ site. Both a spontaneous magnetic order observed with $\mu$SR
and a dispersive spin-wave spectrum observed with inelastic neutron scattering
suggest a model wherein planar dipoles order antiferromagnetically. Notable
inconsistencies between $\mu$SR and neutron scattering data within the dipole
picture provide strong evidence for the ordering of higher-order moments.

Strongly Correlated Electrons