Evidence for a quantum dipole liquid state in an organic quasi-two-dimensional material

Abstract

Mott insulators are commonly pictured with electrons localized on lattice sites. Their low-energy degrees of freedom involve spins only. Here we observe emerging charge degrees of freedom in a molecule-based Mott insulator $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br, resulting in a quantum dipole liquid state. Electrons localized on molecular dimer lattice sites form electric dipoles that do not order at low temperatures and fluctuate with frequency detected experimentally in our Raman spectroscopy experiments. The heat capacity and Raman scattering response are consistent with a scenario where the composite spin and electric dipole degrees of freedom remain fluctuating down to the lowest measured temperatures.

References in corpus (11)

• Quantum Spin Liquid States
• Inelastic Light Scattering From Correlated Electrons
• Absence of charge order in the dimerized κ-phase BEDT-TTF salts
• A Spin-Orbital Singlet and Quantum Critical Point on the Diamond Lattice: FeSc2S4
• A Quantum Dipolar Spin Liquid
• Quantum electric-dipole liquid on a triangular lattice
• Raman scattering in a Heisenberg {\boldmath $S=1/2$} antiferromagnet on the triangular lattice
• Metal-Insulator Transition in the Dimerized Organic Conductor $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• Dynamical reduction of the dimensionality of exchange interactions and the "spin-liquid" phase of $\kappa$-(BEDT-TTF)${}_{2}X$
• Quantum Melting of Magnetic Order in an Organic Dimer-Mott Insulating System
• Antiferromagnetic fluctuations in the quasi-two-dimensional organic superconductor detected by Raman spectroscopy

Cited by in corpus (26)

• Quantum Spin Liquids
• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• Impurity Moments Conceal Low-Energy Relaxation of Quantum Spin Liquids
• Dynamic multiferroicity of a ferroelectric quantum critical point
• Melting of charge order in the low-temperature state of an electronic ferroelectric
• Interplay of dipoles and spins in $\kappa$-(BEDT-TTF)${}_{2}X$, where $X=$ Hg(SCN)${}_2$Cl, Hg(SCN)${}_2$Br, Cu[N(CN)${}_2$]Cl, Cu[N(CN)${}_2$]Br, and Ag${}_2$(CN)${}_3$
• Charge disproportionation in the spin-liquid candidate $\kappa$-(ET)${}_2$Cu${}_2$(CN)${}_3$ at 6 K revealed by ${}^{63}$Cu NQR measurements
• Ingredients for Generalized Models of $\kappa$-Phase Organic Charge-Transfer Salts: A Review
• Weak ferromagnetism and glassy state in kappa-(BEDT-TTF)2Hg(SCN)2Br
• Possible Quantum Paraelectric State in Kitaev Spin Liquid Candidate H${}_3$LiIr${}_2$O${}_6$
• Ferromagnetism out of charge fluctuation of strongly correlated electrons in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• Antiferromagnetic State in $\kappa$-type Molecular Conductors: Spin Splitting and Mott Gap
• Anomalously field-susceptible spin soft-matter emerging in an electric-dipole liquid candidate
• First-principles study of the charge ordered phase in $\kappa$-D${}_3$(Cat-EDT-TTF/ST)${}_2$: Stability of $\pi$-electron deuterium coupled ordering in hydrogen-bonded molecular conductors
• The princess and the pea: on the outsized role of inter-layer ligands in copper-pyrazine antiferromagnets
• Novel Dipole-Lattice coupling in the Quantum-Spin-Liquid Material $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Charge and spin interplay in a molecular-dimer-based organic Mott insulator
• Quantum valence bond ice theory for proton-driven quantum spin-dipole liquids
• A frustrated antipolar phase analogous to classical spin liquids
• Molecular dipoles in designer honeycomb lattices
• Raman Scattering Spectra of Boron Imidazolate Frameworks Containing Different Magnetic Ions
• Absence of superconductivity in the Hubbard dimer model for kappa-(BEDT-TTF)_2X
• Electronic correlations and spin frustration in the molecular conductors $\kappa$-(BEDT-TTF)${}_2$X probed by magnetic quantum oscillations
• Electronic properties of the dimerized organic conductor $\kappa$-(BETS)${}_2$Mn[N(CN)${}_2$]${}_3$
• ${}^{13}$C NMR observation of a nonmagnetic charge-ordered state in the organic conductor $\kappa$-(ET)${}_2$Hg(SCN)${}_2$Cl
• Tuning Charge Order in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$X (X=Br, Cl) via Uniaxial Strain