Thermal-transport measurements in a quantum spin-liquid state of the frustrated triangular magnet -(BEDT-TTF) 2 Cu 2 (CN) 3

Minoru Yamashita, Norihito Nakata, Yuichi Kasahara, Takahiko Sasaki, Naoki Yoneyama, Norio Kobayashi, Satoshi Fujimoto, Takasada Shibauchi, Yuji Matsuda

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Abstract

The notion of quantum spin-liquids (QSLs), antiferromagnets with quantum fluctuation-driven disordered ground states, is now firmly established in one-dimensional (1D) spin systems as well as in their ladder cousins. The spin-1/2 organic insulator -(bis(ethylenedithio)-tetrathiafulvalene) 2 Cu 2 (CN) 3 (-(BEDT-TTF) 2 Cu 2 (CN) 3; ref.1) with a 2D triangular lattice structure is very likely to be the first experimental realization of this exotic state in D2. Of crucial importance is to unveil the nature of the low-lying elementary spin excitations, particularly the presence/absence of a spin gap, which will provide vital information on the universality class of this putative QSL. Here, we report on our thermal-transport measurements carried out down to 80 mK. We find, rather unexpectedly, unambiguous evidence for the absence of a gapless excitation, which sharply contradicts recent reports of heat capacity measurements. The low-energy physics of this intriguing system needs be reinterpreted in light of the present results indicating a spin-gapped QSL phase.

Original languageEnglish
Pages (from-to)44-47
Number of pages4
JournalNature Physics
Volume5
Issue number1
DOIs
Publication statusPublished - 2009 Jan

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Yamashita, M., Nakata, N., Kasahara, Y., Sasaki, T., Yoneyama, N., Kobayashi, N., Fujimoto, S., Shibauchi, T., & Matsuda, Y. (2009). Thermal-transport measurements in a quantum spin-liquid state of the frustrated triangular magnet -(BEDT-TTF) 2 Cu 2 (CN) 3. Nature Physics, 5(1), 44-47. https://doi.org/10.1038/nphys1134