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

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.

arXiv comment4 pages, 4 figures, Supplement, Movie at http://tp2.irb.hr/web/Fononi_Silvia/ (to be published in Physical Review B)

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• The Paired Electron Crystal: order from frustration in the quarter-filled band
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Cited by in corpus (29)

• Quantum Spin Liquid States
• Pressure-Tuned Exchange Coupling of a Quantum Spin Liquid in the Molecular Triangular Lattice $\kappa$-(ET)${}_2$Ag${}_2$(CN)${}_3$
• Gapped magnetic ground state in quantum-spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$-Cu${}_2$(CN)${}_3$
• Quantum Spin Liquids Unveil the Genuine Mott State
• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• Pressure-dependent optical investigations of $\alpha$-(BEDT-TTF)${}_2$I${}_3$: tuning charge order and narrow gap towards a Dirac semimetal
• Anions effects on the electronic structure and electrodynamic properties of the Mott insulator $\kappa$-(BEDT-TTF)${}_2$Ag${}_2$(CN)${}_3$
• Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids
• Metal-Insulator Transition in the Dimerized Organic Conductor $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• Electrodynamics of quantum spin liquids
• Site-specific ${}^{13}$C NMR study on locally distorted triangular lattice of organic conductor $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Coulomb enhancement of superconducting pair-pair correlations in a $\frac{3}{4}$-filled model for $\kappa$-(BEDT-TTF)${}_2$X
• Lattice dynamics in the spin-1/2 frustrated kagome compound herbertsmithite
• 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
• Charge disproportionation in the spin-liquid candidate $\kappa$-(ET)${}_2$Cu${}_2$(CN)${}_3$ at 6 K revealed by ${}^{63}$Cu NQR measurements
• Energy Landscape of Charge Excitations in Boundary Region between Dimer-Mott and Charge Order State in Molecular Solids
• Weak ferromagnetism and glassy state in kappa-(BEDT-TTF)2Hg(SCN)2Br
• Low-Energy Excitations in Quantum Spin-Liquids Identified by Optical Spectroscopy
• Lattice dynamics coupled to charge and spin degrees of freedom in the molecular dimer-Mott insulator $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]Cl
• Importance of van der Waals interactions and cation-anion coupling in an organic quantum spin liquid
• Resonant inelastic x-ray scattering probes the electron-phonon coupling in the spin-liquid kappa-(BEDT-TTF)2Cu2(CN)3
• Algebraic Charge Dynamics of Quantum Spin Liquid b'-EtMe3Sb[Pd(dmit)2]2
• Novel Dipole-Lattice coupling in the Quantum-Spin-Liquid Material $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Possible observation of the signature of the bad metal phase and its crossover to a Fermi liquid in K(BEDT-TTF)2Cu(NCS)2 bulk and nanoparticles by Raman scattering
• Electronic properties of the dimerized organic conductor $\kappa$-(BETS)${}_2$Mn[N(CN)${}_2$]${}_3$
• Charge-Transfer Complex $\kappa$-(BEST)${}_2$Cu${}_2$(CN)${}_3$ Analogous to Organic Spin Liquid Candidate
• Photoinduced Frustration Modulation in $\kappa$-type Quantum Spin Liquid Candidates
• Emergence of a Fluctuating Ground State in Y-kapellasite under Pressure