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

Abstract

We present a multi-frequency Electron Spin Resonance (ESR) study in the range of 4 GHz to 420 GHz of the quasi-one-dimensional, non-dimerized, quarter-filled Mott insulators, delta-(EDT-TTF-CONMe_2)_2X (X=AsF_6, Br). In the high temperature orthorhombic phase above T~190 K, the magnitude and the temperature dependence of the high temperature spin susceptibility are described by a S = 1/2 Heisenberg antiferromagnetic chain with J_AsF6=298 K and J_Br=474 K coupling constants for X=AsF_6 and Br respectively. We estimate from the temperature dependence of the line width an exchange anisotropy, J'/J of ~2 * 10^{-3}. The frequency dependence of the line width and the g-shift have an unusual quadratic dependence in all crystallographic orientations that we attribute to an antisymmetric exchange (Dzyaloshinskii--Moriya) interaction.

6 pages, 6 figures

References in corpus (8)

• Thermodynamics of Spin S = 1/2 Antiferromagnetic Uniform and Alternating-Exchange Heisenberg Chains
• Electron Spin Resonance in S=1/2 antiferromagnetic chains
• Theory of Low Temperature Electron Spin Resonance in Half-integer Spin Antiferromagnetic Chains
• Electron Spin Resonance in sine-Gordon spin chains in the perturbative spinon regime
• Exact Analysis of ESR Shift in the Spin-1/2 Heisenberg Antiferromagnetic Chain
• Spin diffusion and magnetic eigenoscillations confined to single molecular layers in the organic conductors kappa-(BEDT-TTF)_2Cu[N(CN)_2X (X=Cl, Br)
• Microwave frequency modulation in continuous-wave far-infrared ESR utilizing a quasioptical reflection bridge
• Electron spin resonance in the $S$=1/2 quasi-one-dimensional antiferromagnet with Dzyaloshinskii-Moriya interaction BaCu$\_2$Ge$\_2$O$\_7$

Cited by in corpus (5)

• Symmetric and antisymmetric exchange anisotropies in quasi-one-dimensional CuSe${}_2$O${}_5$ as revealed by ESR
• 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
• Relaxation dynamics in the one-dimensional organic charge-transfer salt δ-(EDT-TTF-CONMe${}_2$)${}_2$Br
• Frustration induced one-dimensionality in the isosceles triangular antiferromagnetic lattice of $\delta$-(EDT-TTF-CONMe${}_2$)${}_2$AsF${}_6$