Electronic and magnetic properties of C₆₀ thin films under ambient conditions: A multitechnique study

Abstract

The magnetic and electronic properties of thin C₆₀ films (film thickness ⩾ P4 ML) grown by sublimation in vacuum on oxidized Si, Au, highly oriented pyrolytic graphite and glass, and subsequently exposed to ambient conditions, are investigated by using a multitechnique approach. The films exhibit a structure consisting of nanometric aggregates, whose size increases with film thickness, irrespective of the substrate, although larger aggregates are found on Au substrates. The XPS data indicate no significant degradation of the C₆₀ films, even though significant amounts of oxygen are present. Magnetic properties are characteristic of C₆₀ films exposed to oxygen and light. In contrast, STS measurements show that the local electronic properties are similar to those reported for ultrathin films grown on the same substrates under vacuum. A detailed discussion on the effects of film-thickness and substrate-type on the C₆₀ film properties, under ambient conditions, is presented.