PHASE-TRANSITIONS OF C-60 THIN-FILMS GROWN BY MOLECULAR-BEAM EPITAXY

Epitaxial C-60 monolayer and C-60/Cu multilayer thin films were succes sfully grown on GaAs(111) surfaces by molecular beam epitaxy. It was c onfirmed that these films grew in a close-packed fee configuration. Th e lattice parameters of these films were investigated at temperatures from 300 K to 14 K to study the phase transitions of the C-60 layers. Anomalies of the lattice parameters were observed in both types of fil m at the transition temperature T-C. Although the T-C of the C-60 mono layer film was 20 K lower than that of bulk crystals, the T-C of the C -60/Cu multilayer film was the same as that of bulk crystals. The bulk C-60 Single crystal under hydrostatic pressure was also observed, to compare the epitaxial strains of the C-60 films. The T-C of C-60 molec ules was shifted lower by epitaxial strain, but was shifted higher by the application of hydrostatic pressure.