Thermal transport of organic molecular crystals (DMe-DCNQI)2Li(1-x)Cux and observation of their super-lattice structure by means of synchrotron radiation X-ray

We have measured the thermal conductivity for organic molecular crystals (DMe-DCNQI)(2)Li1-xCux (x = 0, 0.08, and 0.14) over a wide range of temperatures (4 similar to 250 K). A peak can be seen near similar to 20 K. The peak height decreases with decreasing x, and it completely vanishes for x = 0 specimen. This peak is created by a crossover between the phonon mean free path that diverges as T-2 and the phonon specific heat that decreases as T-3. In addition, we have also succeeded in observing the super-lattice patterns of 4k(F) and 2k(F) of (DMe-DCNQI)(2)Li1-xCux (x = 0 and 0.06) accompanied by the Peierls and the spin Peierls transitions by means of the synchrotron radiation X-ray in Tsukuba's Photon Factory. (c) 2005 Elsevier Ltd. All rights reserved.