Characteristic of interface effect in Cu–C60 granular films

In this letter, ${\mathrm{Cu–C}}_{\mathrm{60}}$ 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 ${\mathrm{C}}_{\mathrm{60}}$ is investigated with Raman spectroscopy. The results indicate that the sample has the uniformly granular microstructure. The interaction between ${\mathrm{C}}_{\mathrm{60}}$ and Cu at the ${\mathrm{Cu–C}}_{\mathrm{60}}$ interfaces, which significantly affects the orientational order–disorder phase transition of ${\mathrm{C}}_{\mathrm{60}}$ and induces the phase transition of ${\mathrm{C}}_{\mathrm{60}}$ in the temperature range from 219 to 248 K. The mechanism of the characteristic of such phase transition is discussed.