1. Nearly linear orbital molecules on a pyrochlore lattice.
- Author
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Krajewska, Aleksandra, Yaresko, Alexander N., Nuss, Jürgen, Bette, Sebastian, Gibbs, Alexandra S., Blankenhorn, Marian, Dinnebier, Robert E., Sari, Dita P., Watanabe, Isao, Bertinshaw, Joel, Gretarsson, Hlynur, Kenji Ishii, Daiju Matsumura, Takuya Tsuji, Masahiko Isobe, Keimer, Bernhard, Hidenori Takagi, and Tomohiro Takayama
- Subjects
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SPIN-orbit interactions , *MOLECULAR orbitals , *COVALENT bonds , *LOW temperatures , *HIGH temperatures , *PYROCHLORE - Abstract
The interplay of spin-orbit coupling with other relevant parameters gives rise to the rich phase competition in complex ruthenates featuring octahedrally coordinated Ru4+. While locally, spin-orbit coupling stabilizes a nonmagnetic Jeff = 0 state, intersite interactions resolve one of two distinct phases at low temperatures: an excitonic magnet stabilized by the magnetic exchange of upper-lying Jeff = 1 states or Ru2 molecular orbital dimers driven by direct orbital overlap. Pyrochlore ruthenates A2Ru2O7 (A = rare earth, Y) are candidate excitonic magnets with geometrical frustration. We synthesized In2Ru2O7 with covalent In-O bonds. This pyrochlore ruthenate hosts a local Jeff = 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 A2Ru2O7 compounds. The disproportionation of covalent In-O bonds drives Ru2O molecule formation, quenching not only the local spin-orbit singlet but also geometrical frustration. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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