Influence of impurities on the density of states at the fermi level in the c(6×4)-C60/Ag(100) two-dimensional superstructure

A number of recent results indicate that C60 films can superconduct at considerably high temperatures. The response of a material to impurities can give an information about its superconducting properties when more conventional methods for spotting superconductivity are difficult to apply. While magnetic impurities act as strong Cooper pair breakers in conventional superconductors, nonmagnetic impurities have none or negligible effect. We investigated the influence of magnetic and nonmagnetic impurities on the electronic structure of one monolayer C60 on Ag(100). Preliminary results show that the gap persists in the presence of nonmagnetic Au but it is completely suppressed in the presence of magnetic Fe, as expected for a superconductor. This result gives a support for the possible superconducting scenario in one monolayer C60 on Ag(100) and certainly requires additional experiments to be performed to assure the superconducting character of the film.