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
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Talk DN: Magnetism DN2020: Magnetism


Heiko Trepka (MPI for Solid State Research, Stuttgart)


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)


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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