Abstract
Large quantum fluctuations drive the spins in solids into magnetically disordered phases that are not simply paramagnetic. This class of system includes the valence bond crystals and quantum spin liquids, in which spin singlets—the basic unit of entangled pairs of spins—form solids and liquids, respectively. In both phases, geometrical frustration is expected to play a role. So far, very few candidate quantum-spin-liquid materials have been found, including an organic Mott insulator, κ-(ET)2Cu2(CN)3, which is based on a regular triangular lattice. Here, we report a material, κ-(ET)2B(CN)4, with different geometry—a highly distorted quasi-one-dimensional triangular lattice. The magnetic susceptibility follows that of the spin-1/2 Heisenberg model on this distorted lattice. The material sustains a magnetically disordered Mott insulating state with enhanced quantum fluctuations over a wide temperature range, and undergoes a transition into a spin-gapped phase at 5 K.
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Acknowledgements
This work was supported by JSPS KAKENHI Grant Number 23225005 and 25800204. We thank H. Kageyama for his comments.
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Y.Y. designed the project and carried out the synthesis and X-ray diffraction measurements. H.I. carried out the resistivity measurements, M.M. the magnetic susceptibility and the high-pressure resistivity measurements, Y.S. the 1H NMR measurements, and Y.N. and H.K. the Raman measurements. H.H. supported the synthesis. T.H. collected crystallographic data of some reference salts. T.K. carried out the DFT calculations. The manuscript was written by Y.Y. and C.H. with contributions from Y.S., M.M. and G.S. All authors commented on the manuscript.
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Yoshida, Y., Ito, H., Maesato, M. et al. Spin-disordered quantum phases in a quasi-one-dimensional triangular lattice. Nature Phys 11, 679–683 (2015). https://doi.org/10.1038/nphys3359
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DOI: https://doi.org/10.1038/nphys3359
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