Tuning Charge Order in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$X (X=Br, Cl) via Uniaxial Strain

Abstract

In condensed matter physics, experimental control over material properties reflects a deep understanding of the underlying physics. In recent years, meaningful progress has been made towards a description of the physics of correlated electron systems, but examples of control of these systems remain rare. In this work, we confirm a phase diagram theoretically proposed for organic Mott insulators. We use $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$X (X=Br,Cl) (BEDT-TTF = bis(ethylenedithio)tetrathiafuvalene) materials as experimental realization of the proposed model and demonstrate the ability to tune them both ways across a phase border between a Mott insulator with a uniformly distributed charge and a charge ordered state through the application of uniaxial strain. We induce charge order at 33 K in the quantum dipole liquid material $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br through the application of tensile strain of 0.4% along the c-axis. We suppress charge order down to 10 K in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Cl by applying a tensile strain of 1.6% along the b-axis. We use Raman scattering spectroscopy to probe the charge state through analysis of charge sensitive molecular vibrations and a low frequency mode of collective dipole fluctuations close to the phase border.

References in corpus (25)

• Spin Liquid State in an Organic Mott Insulator with Triangular Lattice
• Variational study of triangular lattice spin-1/2 model with ring exchanges and spin liquid state in κ-(ET)_2 Cu_2 (CN)_3
• Spin-Liquid phase of the Multiple-Spin Exchange Hamiltonian on the Triangular Lattice
• Revision of model parameters for kappa-type charge transfer salts: an ab initio study
• Strain Tunable Semimetal-Topological-Insulator Transition in Monolayer 1T'-WTe2
• Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3
• The Paired Electron Crystal: order from frustration in the quarter-filled band
• A Quantum Dipolar Spin Liquid
• Pressure-Tuned Exchange Coupling of a Quantum Spin Liquid in the Molecular Triangular Lattice $\kappa$-(ET)${}_2$Ag${}_2$(CN)${}_3$
• Evidence for a quantum dipole liquid state in an organic quasi-two-dimensional material
• Drastic suppression of superconducting $T_c$ by anisotropic strain near a nematic quantum critical point
• Strain-tuning of nematicity and superconductivity in single crystals of FeSe
• Evidence for electronically-driven ferroelectricity in the family of strongly correlated dimerized BEDT-TTF molecular conductors
• Collective Charge Excitation in a Dimer Mott Insulating System
• Spin liquid phase due to competing classical orders in the semiclassical theory of the Heisenberg model with ring exchange on an anisotropic triangular lattice
• Spin liquid phase in the semiclassical theory of the Heisenberg model on an anisotropic triangular lattice with ring exchange
• Effect of biaxial strain on the phase transitions of Ca(Fe1-xCox)2As2
• Metal-Insulator Transition in the Dimerized Organic Conductor $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• 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)${}_3$
• Elastoresistive and Elastocaloric Anomalies at Magnetic and Electronic-Nematic Critical Points
• Ferromagnetism out of charge fluctuation of strongly correlated electrons in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br
• Anomalously field-susceptible spin soft-matter emerging in an electric-dipole liquid candidate
• 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