Dec 8 – 10, 2020 Online only
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Critical magnetic fluctuations in Ca2RuO4 studied by neutron spin-echo and triple-axis spectroscopy

Dec 10, 2020, 2:00 PM
15m
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Talk DN: Magnetism DN2020: Magnetism

Speaker

Heiko Trepka (MPI for Solid State Research, Stuttgart)

Description

We report on comprehensive high-resolution linewidth measurements of critical antiferromagnetic fluctuations in Ca$_2$RuO$_4$ (CRO214) performed at the neutron resonance spin-echo spectrometer TRISP at FRM II and the cold triple-axis spectrometer FLEXX at BER II. CRO214 is structurally related to the unconventional superconductor Sr$_2$RuO$_4$ [1] and hosts a complex interplay between magnetic and electronic correlations leading to a novel type of soft-magnetism with strong single-ion anisotropy, and ‘Higgs’ amplitude fluctuations in the spin-wave spectrum, as revealed by recent neutron experiments [2].
In contrast to conventional magnetic phase transitions, the magnetic ordering in CRO214 below T$_N$ ~ 110 K emerges from exciton condensation [3]. Therefore, since the magnetic fluctuations in proximity to T$_N$ are fundamentally related to the nature of the magnetic correlations in the system, our study can shed new light on the exceptional ‘excitonic’ magnetism in CRO214.

[1] Nat. 372, 532, (1994).
[2] Nat. Phys. 13, 633, (2017).
[3] Phys. Rev. Lett. 111, 197201, (2013).

Primary author

Heiko Trepka (MPI for Solid State Research, Stuttgart)

Co-authors

Thomas Keller (MPI for Solid State Research, Stuttgart) Matthias Hepting (Max Planck Institute for Solid State Physics) Dr Maximilian Krautloher (Max-Planck-Institut für Festkörperforschung) Jianhui Xu (MLZ, TUM) Klaus Habicht (Helmholtz-zentrum Berlin für Materialien und Energie) Prof. Bernhard Keimer (Max-Planck-Institut für Festkörperforschung) Dr Juan Porras (Max-Planck-Institut für Festkörperforschung)

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