Quantum Melting of Magnetic Order in an Organic Dimer-Mott Insulating System

Abstract

Quantum entanglement effects between the electronic spin and charge degrees of freedom are examined in an organic molecular solid, termed a dimer-Mott insulating system, in which molecular dimers are arranged in a crystal as fundamental units. A low energy effective model includes an antisymmetric exchange interaction, as one of the dominant magnetic interactions. This interaction favors a 90 degree spin configuration, and competes with the Heisenberg-type exchange interaction. Stabilities of the magnetic ordered phases are examined by using the spin-wave theory, as well as the Schwinger-boson theory. It is found that the spin-charge interaction promotes an instability of the long-range magnetic ordered state around a parameter region where two spin-spiral phases are merged. Implication for the quantum spin liquid state observed in $\kappa$-(BEDT-TTF)${}_2$Cu${}_2$(CN)${}_3$ is discussed.

9 pages, 7 figures

References in corpus (4)

• Spin current and magneto-electric effect in non-collinear magnets
• Spin-orbital quantum liquid on the honeycomb lattice
• Absence of charge order in the dimerized κ-phase BEDT-TTF salts
• Magnetoelectric effect in organic molecular solids

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• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
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• Melting of charge order in the low-temperature state of an electronic ferroelectric
• Importance of van der Waals interactions and cation-anion coupling in an organic quantum spin liquid
• Anomalously field-susceptible spin soft-matter emerging in an electric-dipole liquid candidate
• Charge and spin interplay in a molecular-dimer-based organic Mott insulator
• Quantum valence bond ice theory for proton-driven quantum spin-dipole liquids
• ${}^{13}$C NMR observation of a nonmagnetic charge-ordered state in the organic conductor $\kappa$-(ET)${}_2$Hg(SCN)${}_2$Cl