Magnetoelastic dynamics of the "spin Jahn-Teller" transition in CoTi$_{2}$O$_{5}$

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Auteurs principaux: Guratinder, K., Johnson, R. D., Prabhakaran, D., Taylor, R. A., Lang, F., Blundell, S. J., Taran, L. S., Streltsov, S. V., Williams, T. J., Giblin, S. R., Fennell, T., Schmalzl, K., Stock, C.
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Publié: 2025
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author Guratinder, K.
Johnson, R. D.
Prabhakaran, D.
Taylor, R. A.
Lang, F.
Blundell, S. J.
Taran, L. S.
Streltsov, S. V.
Williams, T. J.
Giblin, S. R.
Fennell, T.
Schmalzl, K.
Stock, C.
author_facet Guratinder, K.
Johnson, R. D.
Prabhakaran, D.
Taylor, R. A.
Lang, F.
Blundell, S. J.
Taran, L. S.
Streltsov, S. V.
Williams, T. J.
Giblin, S. R.
Fennell, T.
Schmalzl, K.
Stock, C.
contents CoTi$_{2}$O$_{5}$ has the paradox that low temperature static magnetic order is incompatible with the crystal structure owing to a mirror plane that exactly frustrates magnetic interactions. Despite no observable structural distortion with diffraction, CoTi$_{2}$O$_{5}$ does magnetically order below $T_{\rm N}$ $\sim$ 25 K with the breaking of spin ground state degeneracy proposed to be a realization of the spin Jahn-Teller effect in analogy to the celebrated orbital Jahn-Teller transition. We apply neutron and Raman spectroscopy to study the dynamics of this transition in CoTi$_{2}$O$_{5}$. We find anomalous acoustics associated with a symmetry breaking strain that characterizes the spin Jahn-Teller transition. Crucially, the energy of this phonon coincides with the energy scale of the magnetic excitations, and has the same symmetry of an optic mode, observed with Raman spectroscopy, which atypically softens in energy with decreasing temperature. Taken together, we propose that the energetics of the spin Jahn-Teller effect in CoTi$_{2}$O$_{5}$ are related to cooperative magnetoelastic fluctuations as opposed to conventional soft critical dynamics which typically drive large measurable static displacements.
format Preprint
id arxiv_https___arxiv_org_abs_2506_16637
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Magnetoelastic dynamics of the "spin Jahn-Teller" transition in CoTi$_{2}$O$_{5}$
Guratinder, K.
Johnson, R. D.
Prabhakaran, D.
Taylor, R. A.
Lang, F.
Blundell, S. J.
Taran, L. S.
Streltsov, S. V.
Williams, T. J.
Giblin, S. R.
Fennell, T.
Schmalzl, K.
Stock, C.
Strongly Correlated Electrons
CoTi$_{2}$O$_{5}$ has the paradox that low temperature static magnetic order is incompatible with the crystal structure owing to a mirror plane that exactly frustrates magnetic interactions. Despite no observable structural distortion with diffraction, CoTi$_{2}$O$_{5}$ does magnetically order below $T_{\rm N}$ $\sim$ 25 K with the breaking of spin ground state degeneracy proposed to be a realization of the spin Jahn-Teller effect in analogy to the celebrated orbital Jahn-Teller transition. We apply neutron and Raman spectroscopy to study the dynamics of this transition in CoTi$_{2}$O$_{5}$. We find anomalous acoustics associated with a symmetry breaking strain that characterizes the spin Jahn-Teller transition. Crucially, the energy of this phonon coincides with the energy scale of the magnetic excitations, and has the same symmetry of an optic mode, observed with Raman spectroscopy, which atypically softens in energy with decreasing temperature. Taken together, we propose that the energetics of the spin Jahn-Teller effect in CoTi$_{2}$O$_{5}$ are related to cooperative magnetoelastic fluctuations as opposed to conventional soft critical dynamics which typically drive large measurable static displacements.
title Magnetoelastic dynamics of the "spin Jahn-Teller" transition in CoTi$_{2}$O$_{5}$
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2506.16637