Pseudo-chiral phonon splitting from octupolar magnetic order

Fuente: arXiv
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Main Authors: Sutcliffe, Ruairidh, Hart, Kathleen, Chaudhary, Swati, Paramekanti, Arun
Format: Preprint
Published: 2025
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author Sutcliffe, Ruairidh
Hart, Kathleen
Chaudhary, Swati
Paramekanti, Arun
author_facet Sutcliffe, Ruairidh
Hart, Kathleen
Chaudhary, Swati
Paramekanti, Arun
contents Motivated by the recent discovery of anomalously large magnetic response of chiral phonons in dipolar magnets, we explore an extension to study Einstein quantum phonon modes coupled to multipolar moments. We consider the case of non-Kramers $Γ_3$ doublets which encapsulate quadrupolar and Ising octupolar degrees of freedom, and which feature a symmetry-allowed linear coupling between local quadrupolar moments and Raman active $E_g$ phonon modes $(d_{x^2-y^2},d_{3z^2-r^2})$. We show that either octupolar or quadrupolar ordering leads to degeneracy breaking of the $E_g$ phonon doublet, with ferro-octupolar order favoring pseudo-chiral phonon eigenmodes with a detectable energy splitting. We describe this physics using a path integral approach in the limit where `fast' phonon modes sense the `slow' pseudospins as a static background which we average over using Monte Carlo simulations. We discuss implications for materials such as Ba$_2$CaOsO$_6$ and PrV$_2$Al$_{20}$ where Raman spectroscopy of phonons could be used as a potential probe of hidden octupolar order. Our work extends the important concept of chiral phonons to a large class of multipolar magnets.
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id arxiv_https___arxiv_org_abs_2506_18978
institution arXiv
publishDate 2025
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spellingShingle Pseudo-chiral phonon splitting from octupolar magnetic order
Sutcliffe, Ruairidh
Hart, Kathleen
Chaudhary, Swati
Paramekanti, Arun
Strongly Correlated Electrons
Motivated by the recent discovery of anomalously large magnetic response of chiral phonons in dipolar magnets, we explore an extension to study Einstein quantum phonon modes coupled to multipolar moments. We consider the case of non-Kramers $Γ_3$ doublets which encapsulate quadrupolar and Ising octupolar degrees of freedom, and which feature a symmetry-allowed linear coupling between local quadrupolar moments and Raman active $E_g$ phonon modes $(d_{x^2-y^2},d_{3z^2-r^2})$. We show that either octupolar or quadrupolar ordering leads to degeneracy breaking of the $E_g$ phonon doublet, with ferro-octupolar order favoring pseudo-chiral phonon eigenmodes with a detectable energy splitting. We describe this physics using a path integral approach in the limit where `fast' phonon modes sense the `slow' pseudospins as a static background which we average over using Monte Carlo simulations. We discuss implications for materials such as Ba$_2$CaOsO$_6$ and PrV$_2$Al$_{20}$ where Raman spectroscopy of phonons could be used as a potential probe of hidden octupolar order. Our work extends the important concept of chiral phonons to a large class of multipolar magnets.
title Pseudo-chiral phonon splitting from octupolar magnetic order
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2506.18978