Spectroscopy of the Peierls transition order parameter in the quasi-one dimensional organic conductor (FA)2PF6

Vibrational Properties of Monophosphate Tungsten Bronzes (PO2)4(WO3)2m (m = 4, 6)

“…The intensity (I) of new modes (such as phase phonons) below a transition is proportional to the square of the order parameter (∆); i.e., I ∼ ∆ 2 . 46,47 In Figure 3c, fitting the integrated intensity as ∼(T c -T) 2β (dashed curve) yields T c ) 166 K and β ≈ 0.13. The β value is small compared with the value in a mean field (45) Note that W-O stretching modes of the m ) 4 compound are at lower frequencies compared to those modes of the m ) 6 material because of higher average oxidation states of W in the m ) 6 material.…”

“…The β value is small compared with the value in a mean field (45) Note that W-O stretching modes of the m ) 4 compound are at lower frequencies compared to those modes of the m ) 6 material because of higher average oxidation states of W in the m ) 6 material. (0.5) 48 or a tricritical (0.25) transition, 46 indicating that these models are not applicable here. It is interesting that the absorption spectrum of the m ) 4 compound is dominated by c-axis vibrational modes at room temperature, whereas that of the m ) 6 material exhibits a somewhat richer response.…”

“…The intensity of the 1099 cm -1 mode at temperatures well above T c1 again points toward important fluctuation effects in the MPTB materials. The intensity ( I ) of new modes (such as phase phonons) below a transition is proportional to the square of the order parameter (Δ); i.e., I ∼ Δ 2 . , In Figure c, fitting the integrated intensity as ∼( T c − T ) 2β (dashed curve) yields T c = 166 K and β ≈ 0.13. The β value is small compared with the value in a mean field (0.5) or a tricritical (0.25) transition, indicating that these models are not applicable here.…”

Longitudinal and transverse diffusion of conduction-electron spins on stacks of fluoranthene radical cations

“…17,[20][21][22][23][24] Figure 1 shows examples for the microwave conductivity of typical crystals. The unique property of these arene salts is their extremely narrow conductionelectron spin resonance ͑ESR͒ line, or correspondingly their extremely long transverse as well as spin lattice relaxation times of the order of 5 -10 s. 25 This is a consequence of the conduction electrons' weak spin-orbit coupling and their highly one-dimensional motion.…”