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arXiv · 2105.00251

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

Lena Nadine Majer·Björn Miksch·Olga Iakutkina·Takuya Kobayashi·Atsushi Kawamoto·Martin Dressel
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Abstract

We performed angular and temperature-dependent electron-spin-resonance measurements in the quasi-two-dimensional organic conductor $κ$-(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; $κ$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]I behaves insulating when cooled below $T$ = 200 K. A spin gap ($Δ\approx$ 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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Lena Nadine Majer, Björn Miksch, Olga Iakutkina, Takuya Kobayashi, Atsushi Kawamoto, Martin Dressel. 2021-05-01. Interacting electron spins in $κ$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]I investigated by ESR spectroscopy. https://doi.org/10.1103/physrevb.102.214430

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