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Mar 20 – 23, 2023
Campus Garching
Europe/Berlin timezone

Neutron polarimetry study on the phonon-crystal field coupling in CeAuAl3

Mar 20, 2023, 4:00 PM
Yards 4 - 6 (Fakultät für Maschinenwesen)

Yards 4 - 6

Fakultät für Maschinenwesen

Board: MO-231
Poster Magnetism, Superconductivity, Topological Systems, Magnetic Thin Films an other electronic phenomena Poster Session MONDAY


Michal Stekiel (Technische Universität München)


The magnetoelastic coupling between phonons and f-electron transitions in crystal electric field (CEF) has been of interest for long time already but still lacks a systematic understanding. It was first recognized in 1980s in CeAl2 that showed an unexpected excitation spectrum. It was explained by a qualitative theory developed by Thalmaier and Fulde [2] but limited to this case. Such phonon-CEF coupling in CeAuAl3 seems to be exceptionally interesting. Just as CeAl2 it hosts a coupled phonon-CEF excitation that manifests in the measured spectra as an additional non-dispersive excitation at 8 meV. However, it also shows an anti-crossing of the CEF excitation at 5 meV and an acoustic phonon [3].
We have performed polarized inelastic neutron scattering measurements on CeAuAl3 to elucidate on the polarization of the coupled excitation as well as on the phonon-CEF anti-crossing. We have observed a transfer of the spectral weight between the magnetic and nuclear channels in the anti-crossing region. Most importantly we have adapted and extended the Thalmaier-Fulde model and performed calculations with McPhase software [4] that allow to quantitatively reproduce the measured spectra and the spectral weight transfer.

[1] M. Loewenhaupt et al, Phys. Rev. Lett, 42, 1709, (1979).
[2] P. Thalmeier and P. Fulde, Phys. Rev. Lett., 49, 1588, (1982).
[3] P. Cermak et al, PNAS, 116, 6695-6700, (2019).
[4] M. Rotter et al, J. Phys.: Condens. Matter, 24, 213201, (2012).

Primary authors

Michal Stekiel (Technische Universität München) Petr Čermák (MGML, Charles University) Christian Franz Dr Martin Rotter (McPhase project) Karin Schmalzl (Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at ILL, Grenoble, France) Wolfgang Schmidt (JCNS @ ILL) Christian Pfleiderer Astrid Schneidewind

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