Charge and spin interplay in a molecular-dimer-based organic Mott insulator

Abstract

Triangular lattice quasi-two-dimensional Mott insulators based on BEDT-TTF molecule and its analogies present a possibility to produce exotic phases by coupling charge and spin degrees of freedom. In this work we discuss magnetic properties of one of such materials, $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Cl, which is found at the border of the phase transition between a Mott insulator into a charge ordered state. Our magnetic susceptibility and cantilever magnetisation measurements demonstrate how the charge degree of freedom defines magnetic properties for few different charge phases observed in this material as a function of temperature. Between $T_{CO}=30K$ and $T_S=24K$ we observe charge and spin separation due to one-dimensional charge stripes formed in this material below $T_{CO}=30K$. Below $T_S=24K$ charge and spin degrees of freedom demonstrate coupling. Spin singlet correlations develop below 24~K, however melting of charge order below 15~K prevents the spin singlet state formation, leaving the system in the inhomogeneous state with charge ordered spin singlet domains and charge and spin fluctuating ones.

References in corpus (8)

• Absence of charge order in the dimerized κ-phase BEDT-TTF salts
• Novel Pauli-paramagnetic quantum phase in a Mott insulator
• Ordering phenomena in quasi one-dimensional organic conductors
• Evidence for Ballistic Thermal Conduction in the One-Dimensional S=1/2 Heisenberg Antiferromagnetic Spin System Sr2CuO3
• Raman scattering in a Heisenberg {\boldmath $S=1/2$} antiferromagnet on the triangular lattice
• Phase Competition and Superconductivity in $\kappa$-(BEDT-TTF)${}_2$X: Importance of Intermolecular Coulomb Interactions
• Spin liquid phase in the semiclassical theory of the Heisenberg model on an anisotropic triangular lattice with ring exchange
• Ferromagnetism out of charge fluctuation of strongly correlated electrons in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$Br

Cited by in corpus (3)

• Novel Dipole-Lattice coupling in the Quantum-Spin-Liquid Material $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$
• Tuning Charge Order in $\kappa$-(BEDT-TTF)${}_2$Hg(SCN)${}_2$X (X=Br, Cl) via Uniaxial Strain
• ${}^{13}$C NMR observation of a nonmagnetic charge-ordered state in the organic conductor $\kappa$-(ET)${}_2$Hg(SCN)${}_2$Cl