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arXiv · 2103.12249

Magnetic field-driven transition between valence bond solid and antiferromagnetic order in distorted triangular lattice

Yasuhiro Shimizu·Mitsuhiko Maesato·Makoto Yoshida·Masashi Takigawa·Masayuki Itoh·Akihiro Otsuka·Hideki Yamochi·Yukihiro Yoshida·Genta Kawaguchi·David Graf·Gunzi Saito
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Abstract

A molecular Mott insulator $κ$-(ET)$_2$B(CN)$_4$ [ET = bis(ethylenedithio)tetrathiafulvalene] with a distorted triangular lattice exhibits a quantum disordered state with gapped spin excitation in the ground state. $^{13}$C nuclear magnetic resonance, magnetization, and magnetic torque measurements reveal that magnetic field suppresses valence bond order and induces long-range magnetic order above a critical field $\sim 8$ T. The nuclear spin-lattice relaxation rate $1/T_1$ shows persistent evolution of antiferromagnetic correlation above the transition temperature, highlighting a quantum spin liquid state with fractional excitations. The field-induced transition as observed in the spin-Peierls phase suggests that the valence bond order transition is driven through renormalized one-dimensionality and spin-lattice coupling.

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Yasuhiro Shimizu, Mitsuhiko Maesato, Makoto Yoshida, Masashi Takigawa, Masayuki Itoh, Akihiro Otsuka, Hideki Yamochi, Yukihiro Yoshida, Genta Kawaguchi, David Graf, Gunzi Saito. 2021-03-23. Magnetic field-driven transition between valence bond solid and antiferromagnetic order in distorted triangular lattice. https://doi.org/10.1103/physrevresearch.3.023145

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