Direct confirmation of long-range magnetic order and evidence for multipoles in Ce$_{2}$O$_{3}$

Alexandra Cote; J. Eddie Slimak; Astha Sethi; Dalmau Reig-i-Plessis; Qiang Zhang; Yang Zhao; Devashibhai Adroja; Gerald Morris; Taras Kolodiazhnyi; Alannah M. Hallas; Jeffrey W. Lynn; S. Lance Cooper; Gregory J. MacDougall

arXiv · 2303.11878

Direct confirmation of long-range magnetic order and evidence for multipoles in Ce$_{2}$O$_{3}$

Alexandra Cote·J. Eddie Slimak·Astha Sethi·Dalmau Reig-i-Plessis·Qiang Zhang·Yang Zhao·Devashibhai Adroja·Gerald Morris·Taras Kolodiazhnyi·Alannah M. Hallas·Jeffrey W. Lynn·S. Lance Cooper·Gregory J. MacDougall

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Abstract

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.

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Alexandra Cote, J. Eddie Slimak, Astha Sethi, Dalmau Reig-i-Plessis, Qiang Zhang, Yang Zhao, Devashibhai Adroja, Gerald Morris, Taras Kolodiazhnyi, Alannah M. Hallas, Jeffrey W. Lynn, S. Lance Cooper, Gregory J. MacDougall. 2023-03-21. Direct confirmation of long-range magnetic order and evidence for multipoles in Ce$_{2}$O$_{3}$. https://arxiv.org/abs/2303.11878

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