Charge-density fluctuations probed by vibronic modes of K0.3MoO3

Polarized reflection measurements have been performed on the charge-density-wave compound K0.3MoO3 from room temperature down to T=50 K. For the first time, the least conducting direction (perpendicular to the planes of MoO6-octahedrons) was investigated in the entire infrared range of frequency. The diatomic MoO stretching vibrations centered around 940 cm−1 exhibit an unusual temperature dependence; below some characteristic temperature T⁎≈200K the line shape changes significantly. The observed features are attributed to change-density-wave fluctuations that are present well above the charge-density-wave transition TCDWTCDW, and start to develop short-range order at T⁎.