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arXiv · 1803.07081

Emergent spin-$1$ Haldane gap and ferroelectricity in a frustrated spin-$1/2$ ladder

Hiroshi Ueda·Shigeki Onoda·Yasuhiro Yamaguchi·Tsuyoshi Kimura·Daichi Yoshizawa·Toshiaki Morioka·Masayuki Hagiwara·Masato Hagihala·Minoru Soda·Takatsugu Masuda·Toshiro Sakakibara·Keisuke Tomiyasu·Seiko Ohira-Kawamura·Kenji Nakajima·Ryoichi Kajimoto·Mitsutaka Nakamura·Yasuhiro Inamura·N. Reynolds·M. Frontzek·J. S. White·Masashi Hase·Yukio Yasui
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Abstract

We report experimental and theoretical evidence that Rb$_2$Cu$_2$Mo$_3$O$_{12}$ has a nonmagnetic tetramer ground state of a two-leg ladder comprising antiferromagnetically coupled frustrated spin-$1/2$ chains and exhibits a Haldane spin gap of emergent spin-1 pairs. Three spin excitations split from the spin-1 triplet by a Dzyaloshinskii-Moriya interaction are identified in inelastic neutron-scattering and electron spin resonance spectra. A tiny magnetic field generates ferroelectricity without closing the spin gap, indicating a novel class of ferroelectricity induced by a vector spin chirality order.

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Hiroshi Ueda, Shigeki Onoda, Yasuhiro Yamaguchi, Tsuyoshi Kimura, Daichi Yoshizawa, Toshiaki Morioka, Masayuki Hagiwara, Masato Hagihala, Minoru Soda, Takatsugu Masuda, Toshiro Sakakibara, Keisuke Tomiyasu, Seiko Ohira-Kawamura, Kenji Nakajima, Ryoichi Kajimoto, Mitsutaka Nakamura, Yasuhiro Inamura, N. Reynolds, M. Frontzek, J. S. White, Masashi Hase, Yukio Yasui. 2020-04-03. Emergent spin-$1$ Haldane gap and ferroelectricity in a frustrated spin-$1/2$ ladder. https://doi.org/10.1103/physrevb.101.140408

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