Phase coexistence at the first-order Mott-transition revealed by pressure-dependent dielectric spectroscopy of $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$

Abstract

The dimer Mott insulator $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$ can be tuned into a metallic and superconducting state upon applying pressure of 1.5 kbar and more. We have performed dielectric spectroscopy measurements (7 kHz to 5 MHz) on $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$ single crystals as a function of temperature (down to $T=8$ K) and pressure (up to $p=4$ kbar). At ambient conditions, a relaxor-like dielectric behavior develops below 50 K that shifts toward lower temperatures as the crystal is pressurized. Interestingly, a second peak emerges in ${\epsilon }_1(T)$ around $T=15$ K, which becomes strongly enhanced with pressure and is attributed to a small volume fraction of metallic puddles in the insulating host phase. When approaching the phase boundary, this peak diverges rapidly reaching ${\epsilon }_1\approx 10^5$. Our dynamical mean-field theory calculations substantiate that the dielectric catastrophe at the Mott transition is not caused by closing the energy gap, but due to the spatial coexistence of correlated metallic and insulating regions. We discuss the percolative nature of the first-order Mott insulator-to-metal transition in all details.

References in corpus (50)

• Anderson Transitions
• Quantum Spin Liquids
• Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging
• Quantum Spin Liquid States
• Spin Liquid State in an Organic Mott Insulator with Triangular Lattice
• Electronic crystals: an experimental overview
• Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors
• Universality and Critical Behavior at the Mott transition
• Mott Transition from a Spin Liquid to a Fermi Liquid in the Spin-Frustrated Organic Conductor kappa-(ET)2Cu2(CN)3
• Quantum frustration in organic Mott insulators: from spin liquids to unconventional superconductors
• Unconventional critical behaviour in a quasi-two-dimensional organic conductor
• Mott transition and transport crossovers in the organic compound $\kappa -(BEDT-TTF{)}_{2}Cu[N(CN{)}_2]Cl$
• How bad metals turn good: spectroscopic signatures of resilient quasiparticles
• Mott--Hubbard transition vs. Anderson localization of correlated, disordered electrons
• Multiferroicity in an organic charge-transfer salt: Electric-dipole-driven magnetism
• Dielectric properties of ultrathin metal films around the percolation threshold
• Theoretical Studies of Superconductor-Insulator Transitions
• Anomalous dielectric response in the dimer Mott insulator $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Emergence of inhomogeneous moments from spin liquid in the triangular-lattice Mott insulator $\kappa$-(ET)${}_2$Cu${}_2$(CN)${}_3$
• Quantum Critical Transport Near the Mott Transition
• Nanoscale imaging of the electronic and structural transitions in vanadium dioxide
• Dielectric catastrophe at the Mott transition
• Lattice effects and entropy release at the low-temperature phase transition in the spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Absence of charge order in the dimerized κ-phase BEDT-TTF salts
• Finite temperature crossovers and the quantum Widom line near the Mott transition
• The Paired Electron Crystal: order from frustration in the quarter-filled band
• Bad-metal behavior reveals Mott quantum criticality in doped Hubbard models
• Quantum Spin Liquids Unveil the Genuine Mott State
• The Paired-Electron Crystal in the Two-Dimensional Frustrated Quarter-Filled Band
• Anisotropic charge dynamics in the quantum spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Imaging phase separation near the Mott boundary in the correlated organic superconductors $\kappa$-(BEDT-TTF)${}_2$X
• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• 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
• Relaxor ferroelectricity induced by electron correlations in a molecular dimer Mott insulator
• Quasi-continuous transition from a Fermi liquid to a spin liquid
• Wigner-Mott scaling of transport near the two-dimensional metal-insulator transition
• Anions effects on the electronic structure and electrodynamic properties of the Mott insulator $\kappa$-(BEDT-TTF)${}_2$Ag${}_2$(CN)${}_3$
• Signature of Electronic Correlations in the Optical Conductivity of the Doped Semiconductor Si:P
• Dynamical mean-field theory of a double-exchange model with diagonal disorder
• Slowing down of the relaxational dynamics at the ferroelectric phase transition in one-dimensional (TMTTF)2AsF6
• Low-Temperature Dielectric Anomalies at the Mott Insulator-Metal Transition
• Mott quantum criticality in the one-band Hubbard model: Dynamical mean-field theory, power-law spectra, and scaling
• Electrodynamics of quantum spin liquids
• Microscopic nature of the asymmetric hysteresis in the insulator-metal transition of VO${}_2$ revealed by spectroscopic ellipsometry
• Highly repeatable nanoscale phase coexistence in vanadium dioxide films
• Beyond the quantum spin liquid concept in frustrated two dimensional organic superconductors
• Low-temperature lattice effects in the spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Energy Landscape of Charge Excitations in Boundary Region between Dimer-Mott and Charge Order State in Molecular Solids
• Low-Energy Excitations in Quantum Spin-Liquids Identified by Optical Spectroscopy
• Importance of van der Waals interactions and cation-anion coupling in an organic quantum spin liquid

Cited by in corpus (8)

• Spectral function of the $J_1-J_2$ Heisenberg model on the triangular lattice
• Dielectric catastrophe at the Mott and Wigner transitions in a moiré superlattice
• Griffiths-like phase close to the Mott transition
• Ingredients for Generalized Models of $\kappa$-Phase Organic Charge-Transfer Salts: A Review
• Persistence of fermionic spin excitations through a genuine Mott transition in $\kappa$-type organics
• Quantum discontinuity fixed point and renormalization group flow of the SYK model
• Charge imbalance in $\lambda$-(BETS)${}_2$GaCl${}_4$ and their interplay with superconductivity
• Charge localization in strongly correlated $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]I due to inherent disorder