Characteristic of interface effect in Cu-C₆₀ granular films

In this letter, Cu-C₆₀ granular film is prepared with coevaporation method at room temperature. The conductance of the film is measured by in situ method, and its microstructure is characterized by transmission electron microscopy. The charge transfer from Cu to C₆₀ is investigated with Raman spectroscopy. The results indicate that the sample has the uniformly granular microstructure. The interaction between C₆₀ and Cu at the Cu-C₆₀ interfaces, which significantly affects the orientational order-disorder phase transition of C₆₀ and induces the phase transition of C₆₀ in the temperature range from 219 to 248 K. The mechanism of the characteristic of such phase transition is discussed.