Thermodynamic properties of a spin-1/2 spin-liquid state in a κ-type organic salt
Author: ["Satoshi Yamashita","Yasuhiro Nakazawa","Masaharu Oguni","Yugo Oshima","Hiroyuki Nojiri","Yasuhiro Shimizu","Kazuya Miyagawa","Kazushi Kanoda"]
Publication: Nature Physics
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Abstract
Spins in a two-dimensional triangular lattice are geometrically frustrated and cannot form an ordered ground state. Instead, a spin-liquid state is expected, and now thermodynamic measurements suggest that a spin liquid exists down to the lowest temperatures. In two-dimensional triangular lattices, geometric frustration prohibits the formation of ordering even at the lowest temperatures, and therefore a liquid-like ground state is expected. The spin-liquid problem has been one of the central topics of condensed-matter science for more than 30 yr in relation to the resonating-valence-bond model1. One of the characteristic features proposed is the existence of a linear temperature-dependent contribution to the heat capacity, as the degeneracy of the energy states should give rise to gapless excitations. Here, we show thermodynamic evidence for the realization of a spin-liquid ground state through a single-crystal calorimetric study of the dimer-based organic charge-transfer salt κ-(BEDT-TTF)2Cu2(CN)3, with a triangular lattice structure down to 75 mK. In addition, we report an unexpected hump structure in the heat capacity around 6 K, which may indicate a crossover into the quantum spin liquid.
Cite this article
Yamashita, S., Nakazawa, Y., Oguni, M. et al. Thermodynamic properties of a spin-1/2 spin-liquid state in a κ-type organic salt. Nature Phys 4, 459–462 (2008). https://doi.org/10.1038/nphys942
