Spin diffusion and magnetic eigenoscillations confined to single molecular layers in the organic conductors kappa-(BEDT-TTF)_2Cu[N(CN)_2X (X=Cl, Br)

Abstract

The layered organic compounds, kappa-(BEDT-TTF)_2Cu[N(CN)_2X (X=Cl, Br) are metals at ambient temperatures. At low temperatures, the Cl compound is a weakly ferromagnetic Mott insulator while the isostructural Br compound is a superconductor. We find by conduction electron spin resonance (CESR) and antiferromagnetic resonance (AFMR) an extreme anisotropy of spin transport and magnetic interactions in these materials. In the metallic state spin diffusion is confined to single molecular layers within the spin lifetime of 10^-9 s. Electrons diffuse several hundreds of nm without hopping to the next molecular layer. In the magnetically ordered insulating phase of the Cl compound we observe and calculate the four AFMR modes of the weakly coupled single molecular layers. The inter-plane exchange field is comparable or less than the typically 1 mT dipolar field and almost 10^6 times less than the intra-layer exchange field.

4 pages, 4 figures, submitted to Phys. Rev. Lett

References in corpus (5)

• Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors
• Test for interlayer coherence in a quasi-two-dimensional superconductor
• Incoherent Interplane Conductivity of kappa-(BEDT-TTF)2Cu[N(CN)2]Br
• Angle-dependent magnetoresistance in the weakly incoherent interlayer transport regime
• Spin-zero anomaly in the magnetic quantum oscillations of a two-dimensional metal

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• Importance of Spin-Orbit Coupling in Organic BEDT-TTF and BEDT-TSF Salts
• Molecular Quantum Materials: Electronic Phases and Charge Dynamics in Two-Dimensional Organic Solids
• Power-law dependence of the optical conductivity observed in the quantum spin-liquid compound κ-(BEDT-TTF)2Cu2(CN)3
• Electron spin dynamics of two-dimensional layered materials
• Inter-layer spin diffusion and electric conductivity in the organic conductors κ-ET2-Cl and κ-ET2-Br
• Spin dynamics in S = 1/2 antiferromagnetic chain compounds delta-(EDT-TTF-CONMe_2)_2X (X=AsF_6, Br): a multi-frequency Electron Spin Resonance study
• Multipurpose High Frequency Electron Spin Resonance Spectrometer for Condensed Matter Research
• Antiferromagnetic fluctuations in the quasi-two-dimensional organic superconductor detected by Raman spectroscopy
• Two-dimensional magnetism in kappa-(BEDT-TTF)2Cu[N(CN)2]Cl, a spin-1/2 Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interaction
• Interacting electron spins in $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]I investigated by ESR spectroscopy
• ESR Investigations of the Magnetic Anisotropy in $\kappa$-(BETS)${}_2$Mn[N(CN)${}_2$]${}_3$
• Frustration induced one-dimensionality in the isosceles triangular antiferromagnetic lattice of $\delta$-(EDT-TTF-CONMe${}_2$)${}_2$AsF${}_6$