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

Abstract

The Mott insulator ${\beta }^{\prime }$-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.

5 pages, 6 figures

References in corpus (19)

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• Quantum Spin Liquid States
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• An ARPES Study of the Electronic Structure of the Quantum Spin Liquid EtMe3Sb[Pd(dmit)2]2

Cited by in corpus (10)

• Quantum Spin Liquids Unveil the Genuine Mott State
• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids
• Electrodynamics of quantum spin liquids
• Phase coexistence at the first-order Mott-transition revealed by pressure-dependent dielectric spectroscopy of $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Ingredients for Generalized Models of $\kappa$-Phase Organic Charge-Transfer Salts: A Review
• Low-Energy Excitations in Quantum Spin-Liquids Identified by Optical Spectroscopy
• Ferromagnetism out of charge fluctuation of strongly correlated electrons in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• Transition of a prestine Mott insulator to a correlated Fermi liquid: Pressure-dependent optical investigations of a quantum spin liquid
• Thermodynamic, dynamic and transport properties of quantum spin liquid in herbertsmithite from experimental and theoretical point of view