Direct confirmation of long-range magnetic order and evidence for multipoles in CeO

A Cote, JE Slimak, A Sethi, D Reig-i-Plessis… - arXiv preprint arXiv …, 2023 - arxiv.org
A Cote, JE Slimak, A Sethi, D Reig-i-Plessis, Q Zhang, Y Zhao, D Adroja, G Morris…
arXiv preprint arXiv:2303.11878, 2023arxiv.org
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 …
The sesquioxide, CeO, 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 = 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 CeO 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 (SR). Our measurements and subsequent analysis confirm that the transition at T can be associated with the ordering of moments on the Ce site. Both a spontaneous magnetic order observed with SR and a dispersive spin-wave spectrum observed with inelastic neutron scattering suggest a model wherein planar dipoles order antiferromagnetically. Notable inconsistencies between SR and neutron scattering data within the dipole picture provide strong evidence for the ordering of higher-order moments.
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