ISIS Neutron and Muon Source Data Journal

Observing the effect of a Cu/Ni superstructure on the Ce environments inside the heavy-fermion compound Ce(Cu1-xNix)2Ge2

Abstract: In Ce(Cu1-xNix)2Ge2, it has long been thought that chemical pressure mediates the competition of the Kondo and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions leading to the formation of a number of doping-dependent magnetic states. However, this also relies on the assumption that Cu/Ni dopants are randomly arranged as a solid solution. We have now shown that this assumption is incorrect. Indeed, single crystal neutron diffraction has revealed the presence of a superstructure of Cu/Ni manifesting as extra diffraction peaks for x=0.25, 0.25, 0.8. This leads to distinct and periodic Ce sites with different oxidation states. This is a crucial discovery as it could mean that not all the Ce sites are Kondo compensated or only some of them contribute to the anti-ferromagnetic order. To study these possible effects, we propose to carry out inelastic neutron scattering measurements using the spectrometer MARI on two samples: CeCuNiGe2 (known superstructure) and CeNi2Ge2 (no superstructure). In this way, we will be able to map out the crystal field levels and recognise if there is additional splitting of these in the superstructure compound. And if so, relate this to the different Ce sites. Observing such splitting would be a truly novel discovery which has the potential of re-defining how heavy-fermion magnetism is interpreted, surely leading to a high impact publication.

Principal Investigator: Miss Eva Bervas
Experimenter: Dr Monica Ciomaga Hatnean
Local Contact: Dr Duc Le

DOI: 10.5286/ISIS.E.RB2690051

ISIS Experiment Number: RB2690051

Publisher: STFC ISIS Neutron and Muon Source

Data format: RAW/Nexus
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Data Citation

The recommended format for citing this dataset in a research publication is as:
[author], [date], [title], [publisher], [doi]

For Example:
Miss Eva Bervas et al; (2026): Observing the effect of a Cu/Ni superstructure on the Ce environments inside the heavy-fermion compound Ce(Cu1-xNix)2Ge2, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2690051

Data is released under the CC-BY-4.0 license.