Fig. 8. Temperature-dependent physical properties of single-crystal 2S–F₄ upon cooling.

a Electrical resistivity. b Polarized reflectivity for photon energies of 144–178 meV in the electric field of light parallel to the π-stacking direction. c Real part of the dielectric constant ε_r at 1.0 MHz. d Normalized χ_spin determined from the calculation using the intensity and ΔB_pp of the electron spin resonance (ESR) signals at g ≈ 2.003. The values are normalized by the value at 340 K, with error bars (standard deviation). e ΔB_pp of the ESR signals at g ≈ 2.003, with error bars (standard deviation). Gray panel indicates the transition temperature around 282 K.