Frustrated random-singlet state with ice-type structural fluctuation in spinel titanates

In ice, it is well known that the orientation of H<sub>2</sub>O molecules is disordered by geometrical frustration. Ice-analogous materials having a pyrochlore lattice display interesting phenomena such as the spin-ice state and the magnetic monopole. In the spinel titanate MgTi<sub>2</sub>O<sub>4</sub>, the Ti ions have a quantum spin in the pyrochlore lattice. The Ti ions are displaced, accompanied by the spin-singlet formation. Since this displacement pattern follows the ice rule, the title compound is a material analogous to ice. When a small quantity of Ti ions are replaced with Mg ions, the ice-type structural fluctuation exists. In this structural ice-type state, the spins are also fluctuating at a nanosecond scale down to 0.3 K. We ascribed this phenomenon to the gapless frustrated random-singlet state, in which the spin-singlet pairs are resonating, and the orphan spins are hopping.

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Publication Details

Journal
Proceedings of the National Academy of Sciences
Published
2025-12-30
DOI
https://doi.org/10.1073/pnas.2517926123
Primary Topic
Advanced Condensed Matter Physics
Type
article
Field-Weighted Citation Impact
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article

Frustrated random-singlet state with ice-type structural fluctuation in spinel titanates

Isao Watanabe, Noriaki Hanasaki, A. Koda, H. Murakawa et al.
Proceedings of the National Academy of Sciences
Advanced Condensed Matter Physics
article

Frustrated random-singlet state with ice-type structural fluctuation in spinel titanates

Isao Watanabe, Noriaki Hanasaki, A. Koda, H. Murakawa, Hidekazu Mukuda, Kouhei YOSHIMI, Yasuhiro Nakazawa, HIDEAKI SAKAI, Hajime Sagayama, Katsuaki Kodama, Mitsuharu YASHIMA, Toshiya Otomo, Takumi Komoda, Satoshi Yamashita, Shuhei Torigoe, Takayuki Hattori, Takashi Honda, Utami Widyaiswari, Kouei Minamoto, Takehiko Nakano
article en

Abstract

In ice, it is well known that the orientation of H<sub>2</sub>O molecules is disordered by geometrical frustration. Ice-analogous materials having a pyrochlore lattice display interesting phenomena such as the spin-ice state and the magnetic monopole. In the spinel titanate MgTi<sub>2</sub>O<sub>4</sub>, the Ti ions have a quantum spin in the pyrochlore lattice. The Ti ions are displaced, accompanied by the spin-singlet formation. Since this displacement pattern follows the ice rule, the title compound is a material analogous to ice. When a small quantity of Ti ions are replaced with Mg ions, the ice-type structural fluctuation exists. In this structural ice-type state, the spins are also fluctuating at a nanosecond scale down to 0.3 K. We ascribed this phenomenon to the gapless frustrated random-singlet state, in which the spin-singlet pairs are resonating, and the orphan spins are hopping.

Proceedings of the National Academy of SciencesVol. 123(1)
Japan Atomic Energy Agency (JP), High Energy Accelerator Research Organization (JP), Osaka University of Economics (JP), Tohoku University (JP), Japan Proton Accelerator Research Complex (JP), Spintronics Research Network of Japan (JP), RIKEN Nishina Center (JP), Ibaraki University (JP), The University of Osaka (JP)
Openalex Percentile: Top 29%
Advanced Condensed Matter Physics
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