Interacting electron spins in $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]I investigated by ESR spectroscopy

Abstract

We performed angular and temperature-dependent electron-spin-resonance measurements in the quasi-two-dimensional organic conductor $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]I. The interlayer spin-diffusion is much weaker compared to the Cl- and Br-analogues, which are antiferromagnetic insulator and paramagnetic metal, respectively; $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]I behaves insulating when cooled below $T$ = 200 K. A spin gap ($\Delta \approx$ 18 K) opens at low temperatures leading to a spin-singlet state. Due to intrinsic disorder a substantial number of spins ($\sim$ 1 $\%$) remains unpaired. We observe additional signals below $T$ = 4 K with a pronounced anisotropy indicating the presence of local magnetic moments coupled to some fraction of those unpaired spins.

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

Cited by in corpus (2)

• Electron spins interaction in the spin-Peierls phase of the organic spin chain (o -DMTTF) 2 X (X = Cl, Br, I)
• Charge localization in strongly correlated $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]I due to inherent disorder