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arXiv · 1710.01942

Importance of van der Waals interactions and cation-anion coupling in an organic quantum spin liquid

P. Lazić·M. Pinterić·D. Rivas Góngora·A. Pustogow·K. Treptow·T. Ivek·O. Milat·B. Gumhalter·N. Došlić·M. Dressel·S. Tomić
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Abstract

The Mott insulator $β'$-EtMe$_3$Sb[Pd(dmit)$_2$]$_2$ belongs to a class of charge transfer solids with highly-frustrated triangular lattice of $S=1/2$ molecular dimers and a quantum-spin-liquid ground state. Our experimental and ab initio theoretical studies show the fingerprints of strong correlations and disorder, important role of cation-dimer bonding in charge redistribution, no sign of intra- and inter-dimer dipoles, and the decisive van der Waals contribution to inter-dimer interactions and the ground state structure. The latter consists of quasi-degenerate electronic states related to the different configurations of cation moieties which permit two different equally probable orientations. Upon reducing the temperature, the low-energy excitations slow down, indicating glassy signatures as the cation motion freezes out.

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P. Lazić, M. Pinterić, D. Rivas Góngora, A. Pustogow, K. Treptow, T. Ivek, O. Milat, B. Gumhalter, N. Došlić, M. Dressel, S. Tomić. 2017-12-27. Importance of van der Waals interactions and cation-anion coupling in an organic quantum spin liquid. https://doi.org/10.1103/physrevb.97.245134

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