Tuning interactions in the spin-ice materials Dy\(_2\)Ge\(_{2-x}\)Si\(_x\)O\(_7\) by silicon substitution

We report that the lattice constant of Dy\(_2\)Ge\(_{2-x}\)Si\(_x\)O\(_7\) (\(x=0, 0.02, 0.08, 0.125\)) can be systematically reduced by substituting the non-magnetic germanium ion in the cubic pyrochlore oxide with silicon. A multi-anvil high-pressure synthesis was performed up to 16 GPa and 1100 \...

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Bibliographic Details
Published in:arXiv.org 2019-08
Main Authors: Stöter, T, Antlauf, M, Opherden, L, Gottschall, T, Hornung, J, Gronemann, J, Herrmannsdörfer, T, Granovsky, S, Schwarz, M, Doerr, M, H -H Klauss, Kroke, E, Wosnitza, J
Format: Article
Language:English
Subjects:
Antiferromagnetism
Germanium
Heat exchange
Lattice parameters
Long range order
Magnetic permeability
Silicon
Specific heat
Substitution reactions
Temperature dependence
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Summary:We report that the lattice constant of Dy\(_2\)Ge\(_{2-x}\)Si\(_x\)O\(_7\) (\(x=0, 0.02, 0.08, 0.125\)) can be systematically reduced by substituting the non-magnetic germanium ion in the cubic pyrochlore oxide with silicon. A multi-anvil high-pressure synthesis was performed up to 16 GPa and 1100 \(^\circ\)C to obtain polycrystalline samples in a solid-state reaction. Measurements of magnetization, ac susceptibility, and heat capacity reveal the typical signatures of a spin-ice phase. From the temperature shift of the peaks, observed in the temperature-dependent heat capacity, we deduce an increase of the strength of the exchange interaction. In conclusion, the reduced lattice constant leads to a changed ratio of the competing exchange and dipolar interaction. This puts the new spin-ice compounds closer towards the phase boundary of short-range spin-ice arrangement and antiferromagnetic long-range order consistent with an observed reduction of the monopole energy scale.
ISSN:2331-8422
DOI:10.48550/arxiv.1809.01480