engleski

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

The Mott insulator β -EtMe3Sb[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, the important role of cation-dimer bonding in charge redistribution, no sign of intra- and interdimer dipoles, and the decisive van der Waals contribution to interdimer interactions and the ground-state structure. The latter consists of quasidegenerate 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.

strongly correlated systems ; mott insulators ; quantum spin liquid ; dielectric properties ; vibrational properties ; density functional theory

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