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Quantum-disordered state of magnetic and electric dipoles in an organic Mott system

2017; Nature Portfolio; Volume: 8; Issue: 1 Linguagem: Inglês

10.1038/s41467-017-01849-x

2041-1723

Masaaki Shimozawa, K. Hashimoto, Akira Ueda, Yoshitaka Suzuki, K. Sugii, Shota Yamada, Y. Imai, Ryota Kobayashi, K. Itoh, Satoshi Iguchi, M. Naka, Sumio Ishihara, Hatsumi Mori, T. Sasaki, Minoru Yamashita,

Perovskite Materials and Applications

Abstract Strongly enhanced quantum fluctuations often lead to a rich variety of quantum-disordered states. Developing approaches to enhance quantum fluctuations may open paths to realize even more fascinating quantum states. Here, we demonstrate that a coupling of localized spins with the zero-point motion of hydrogen atoms, that is, proton fluctuations in a hydrogen-bonded organic Mott insulator provides a different class of quantum spin liquids (QSLs). We find that divergent dielectric behavior associated with the approach to hydrogen-bond order is suppressed by the quantum proton fluctuations, resulting in a quantum paraelectric (QPE) state. Furthermore, our thermal-transport measurements reveal that a QSL state with gapless spin excitations rapidly emerges upon entering the QPE state. These findings indicate that the quantum proton fluctuations give rise to a QSL—a quantum-disordered state of magnetic and electric dipoles—through the coupling between the electron and proton degrees of freedom.