${}^{13}$C NMR Study on the Charge-Disproportionated Conducting State in the Quasi-Two-Dimensional Organic Conductor $\alpha$-(BEDT-TTF)${}_2$I${}_3$

Abstract

The conducting state of the quasi-two-dimensional organic conductor, $\alpha$-(BEDT-TTF)${}_2$I${}_3$, at ambient pressure is investigated with ${}^{13}$C NMR measurements, which separate the local electronic states at three nonequivalent molecular sites (A, B, and C). The spin susceptibility and electron correlation effect are revealed in a locally resolved manner. While there is no remarkable site-dependence around room temperature, the local spin susceptibility gradually disproportionates among the nonequivalent sites with decreasing temperature. The disproportionation-ratio yields 5:4:6 for A:B:C molecules at 140 K. Distinct site- and temperature-dependences are also observed in the Korringa ratio, ${\mathcal{K}}_i\propto (1/T_{1}T{)}_i{K}_i^{-2}$ ($i$ = A, B, and C), which is a measure of the strength and the type of electron correlations. The values of ${\mathcal{K}}_i$ point to sizable antiferromagnetic spin correlation. We argue the present results in terms of the theoretical prediction of the peculiar site-specific reciprocal-space ($\mathbf{k}$-space) anisotropy on the tilted Dirac cone, and discuss the $\mathbf{k}$-dependent profiles of the spin susceptibility and electron correlation on the cone.

12 figures

References in corpus (6)

• Tilted anisotropic Dirac cones in quinoid-type graphene and alpha-(BEDT-TTF)_2I_3
• Charge Ordering in alpha-(BEDT-TTF)2I3 by synchrotron x-ray diffraction
• Effects of the Zero-Mode Landau Level on Inter-Layer Magnetoresistance in Multilayer Massless Dirac Fermion Systems
• Electronic Properties Close to Dirac Cone in Two-Dimensional Organic Conductor $\alpha$-(BEDT-TTF)${}_2$I${}_3$
• Spin and Valley Splittings in Multilayered Massless Dirac Fermion System
• Unusual hyperfine interaction of Dirac electrons and NMR spectroscopy in graphene

Cited by in corpus (17)

• Observation of an anisotropic Dirac cone reshaping and ferrimagnetic spin polarization in an organic conductor
• Anomalous Spin Correlations and Mass-Generating Excitonic Instability of Interacting Weyl Fermions
• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• Pressure-dependent optical investigations of $\alpha$-(BEDT-TTF)${}_2$I${}_3$: tuning charge order and narrow gap towards a Dirac semimetal
• Magnetoplasmons of the tilted-anisotropic Dirac cone material $\alpha -$(BEDT-TTF)${}_2$I${}_3$
• Normal state ${}^{17}$O NMR studies of Sr${}_2$RuO${}_4$ under uniaxial stress
• Synthetic non-Abelian gauge fields and gravitomagnetic effects in tilted Dirac cone systems
• Correlation Effects on Charge Order and Zero-Gap State in the Organic Conductor α-(BEDT-TTF)2I3
• Spin excitations in the quasi-two-dimensional charge-ordered insulator $\alpha$-(BEDT-TTF)${}_2$I${}_3$ probed via ${}^{13}$C NMR
• Effects of Zeroline and Ferrimagnetic Fluctuation on Nuclear Magnetic Resonance for Dirac Electrons in Molecular Conductor alpha-(BEDT-TTF)2I3
• Three-quarter Dirac points, Landau levels and magnetization in $\alpha$-(BEDT-TTF)${}_2$I${}_3$
• Electron Correlations in the Quasi-Two-Dimensional Organic Conductor $\theta$-(BEDT-TTF)${}_2$I${}_3$ investigated by ${}^{13}$C NMR
• Fast nuclear spin relaxation rates in tilted cone Weyl semimetals: Redshift factors from Korringa relation
• Crossover in Electronic Specific Heat near Narrow-Sense Type-III Dirac Cones
• Enhancements of the 3/2 and 5/2 frequencies of de Haas-van Alphen oscillations near the Lifshitz transition in the two-dimensional compensated metal with overtilted Dirac cones
• Role of hydrogen bonding in charge-ordered organic conductor $\alpha$-(BEDT-TTF)${}_2$I${}_3$ probed by ${}^{127}$I nuclear quadrupole resonance
• ${}^{13}$C NMR observation of a nonmagnetic charge-ordered state in the organic conductor $\kappa$-(ET)${}_2$Hg(SCN)${}_2$Cl