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arXiv · 1808.03868

Critical Spin Liquid versus Valence Bond Glass in Triangular Lattice Organic $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$

Kira Riedl·Roser Valenti·Stephen M. Winter
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Abstract

In the quest for materials with unconventional quantum phases, the organic triangular-lattice antiferromagnet $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ has been extensively discussed as a quantum spin liquid (QSL) candidate. Recently, an intriguing quantum critical behaviour was suggested from low-temperature magnetic torque experiments. Through microscopic analysis of all anisotropic contributions, including Dzyaloshinskii-Moriya and multi-spin scalar chiral interactions, we highlight significant deviations of the experimental observations from a quantum critical scenario. Instead, we show that disorder-induced spin defects provide a comprehensive explanation of the low-temperature properties. These spins are attributed to valence bond defects that emerge spontaneously as the QSL enters a valence bond glass phase at low temperature. This theoretical treatment is applicable to a general class of frustrated magnetic systems and has important implications for the interpretation of magnetic torque, nuclear magnetic resonance, thermal transport and thermodynamic experiments.

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Kira Riedl, Roser Valenti, Stephen M. Winter. 2018-08-11. Critical Spin Liquid versus Valence Bond Glass in Triangular Lattice Organic $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$. https://doi.org/10.1038/s41467-019-10604-3

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