Conductive nanodots on the surface of irradiated CaF2

CaF2(111) single crystal surfaces, have been irradiated with fast heavy ions under oblique angles resulting in chains of nanosized hillocks. In order to characterize, these nanodots with respect to their conductivity we have applied noncontact atomic force microscopy using a magnetic tip. Measurements in ultra high vacuum as well as under ambient conditions reveal a clearly enhanced electromagnetic interaction between the magnetic tip. and the nanodots. The dissipated energy per cycle is comparable to the value found for metals indicating that the interaction of the ion with the target material leads to the creation of metallic Ca nanodots on the surface. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim