Raman study of charge-density-wave phase transition in quasi-one-dimensional conductor (TaSe4)2I |
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Authors: | Tomoyuki Sekine Taisaku Seino Mitsuru Izumi Etsuyuki Matsuura |
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Institution: | Institute of Physics, University of Tsukuba, Sakura-mura, Ibaraki 305, Japan |
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Abstract: | Polarized Raman spectra were obtained in the quasi-one-dimensional conductor (TaSe4)2I above and below the charge-density-wave (CDW) transition temperature (Tc=263 K). The Raman intensities of many peaks become intenser and two of the phonon peaks shift to higher frequency with decreasing temperature. Moreover a new broad peak at about 90 cm?1 and a new peak around 166 cm?1 appear in the low-temperature phase. The polarization characteristic shows that the former is assigned to totally symmetric mode. The damping constant of the phonon at 90 cm?1 increases markedly with increasing temperature. The frequency shifts to higher frequency as the temperature increases and the coupling coefficient is approximately proportional to (Tc?T). This peak becomes Raman active owing to the CDW phase transition. The temperature dependence of the damping constant and the frequency shift may have a relation to the dynamical properties of the CDW phase transition. |
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