Nearly linear orbital molecules on a pyrochlore lattice
The interplay of spin-orbit coupling with other relevant parameters gives rise to the rich phase competition in complex ruthenates featuring octahedrally coordinated Ru<sup>4+</sup>. While locally, spin-orbit coupling stabilizes a nonmagnetic <i>J</i><sub>eff</sub> = 0 state, intersite interactions resolve one of two distinct phases at low temperatures: an excitonic magnet stabilized by the magnetic exchange of upper-lying <i>J</i><sub>eff</sub> = 1 states or Ru<sub>2</sub> molecular orbital dimers driven by direct orbital overlap. Pyrochlore ruthenates <i>A</i><sub>2</sub>Ru<sub>2</sub>O<sub>7</sub> (<i>A</i> = rare earth, Y) are candidate excitonic magnets with geometrical frustration. We synthesized In<sub>2</sub>Ru<sub>2</sub>O<sub>7</sub> with covalent In─O bonds. This pyrochlore ruthenate hosts a local <i>J</i><sub>eff</sub> = 0 state at high temperatures; however, at low temperatures, it forms a unique nonmagnetic ground state with nearly linear Ru─O─Ru molecules, in stark contrast to other <i>A</i><sub>2</sub>Ru<sub>2</sub>O<sub>7</sub> compounds. The disproportionation of covalent In─O bonds drives Ru<sub>2</sub>O molecule formation, quenching not only the local spin-orbit singlet but also geometrical frustration.
Authors
- Aleksandra Krajewska (ORCID: https://orcid.org/0000-0002-0535-7784)
- H. Gretarsson (ORCID: https://orcid.org/0009-0008-3209-6736)
- J. Bertinshaw
- Isao Watanabe (ORCID: https://orcid.org/0000-0003-4722-8654)
- Dita Puspita Sari (ORCID: https://orcid.org/0000-0002-9309-1970)
- Jürgen Nuß (ORCID: https://orcid.org/0000-0002-0679-0184)
- Takuya Tsuji (ORCID: https://orcid.org/0000-0001-5428-6460)
- Marian Blankenhorn
- T. Takayama (ORCID: https://orcid.org/0000-0002-3492-2025)
- Daiju Matsumura (ORCID: https://orcid.org/0000-0002-4683-4495)
- Sebastian Bette (ORCID: https://orcid.org/0000-0003-3575-0517)
- Kenji Ishii (ORCID: https://orcid.org/0000-0002-6465-8202)
- Masahiko Isobe (ORCID: https://orcid.org/0000-0002-9253-7256)
- Robert E. Dinnebier (ORCID: https://orcid.org/0000-0003-2778-2113)
- Alexandra S. Gibbs (ORCID: https://orcid.org/0000-0002-7012-1831)
- A. N. Yaresko (ORCID: https://orcid.org/0000-0002-7256-6519)
- H. Takagi (ORCID: https://orcid.org/0000-0001-5700-3761)
- B. Keimer (ORCID: https://orcid.org/0000-0001-5220-9023)
Institutions
- University of Stuttgart (DE)
- Japan Atomic Energy Agency (JP)
- Rutherford Appleton Laboratory (GB)
- University of St Andrews (GB)
- Shibaura Institute of Technology (JP)
- Deutsches Elektronen-Synchrotron DESY (DE)
- Max Planck Institute for Solid State Research (DE)
- Center for Integrated Quantum Science and Technology (DE)
- National Institutes for Quantum Science and Technology (JP)
- RIKEN Nishina Center (JP)
- The University of Tokyo (JP)
Publication Details
- Journal
- Science Advances
- Published
- 2024-10-09
- DOI
- https://doi.org/10.1126/sciadv.adn3880
- Citations
- 4
- Primary Topic
- Advanced Condensed Matter Physics
- Type
- article
- Field-Weighted Citation Impact
- 1.24
Funders
- Engineering and Physical Sciences Research Council