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arXiv · 1601.04926

Lattice vibrations of the charge-transfer salt $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_{3}$: novel interpretation of the electrodynamic response in a spin-liquid compound

M. Dressel·P. Lazic·A. Pustogow·E. Zhukova·B. Gorshunov·J. A. Schlueter·O. Milat·B. Gumhalter·S. Tomic
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Abstract

The dimer Mott insulator $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ exhibits unusual electrodynamic properties. Numerical investigations of the electronic ground state and the molecular and lattice vibrations reveal the importance of the Cu$_2$(CN)$_3^-$ anion network coupled to the BEDT-TTF molecules: The threefold cyanide coordination of copper and linkage isomerism in the anion structure cause a loss of symmetry, frustration, disorder, and domain formation. Our findings consistently explain the temperature and polarization-dependent THz and infrared measurements, reinforce the understanding of dielectric properties and have important implications for the quantum spin-liquid state, which should be treated beyond two-dimensional, purely electronic models.

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M. Dressel, P. Lazic, A. Pustogow, E. Zhukova, B. Gorshunov, J. A. Schlueter, O. Milat, B. Gumhalter, S. Tomic. 2016-01-19. Lattice vibrations of the charge-transfer salt $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_{3}$: novel interpretation of the electrodynamic response in a spin-liquid compound. https://doi.org/10.1103/physrevb.93.081201

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