Nanostructuring CaF₂ surfaces with slow highly charged ions

In recent years the potential of slow highly charged ions (HCI) as tools for nanostructuring purposes has received considerable attention and a wide range of material classes, from insulating ionic crystals, polymers and ultrathin films, to semiconducting and conducting substrates have been investigated regarding their response to individual HCI impact. For the majority of investigated materials, however, consistent theoretical modeling to supplement with experimental evidence and to satisfactorily explain the complete physical process from ion approach and impact to the formation of an individual nanostructure is still lacking. CaF₂, from both an experimental and theoretical point of view, might be considered the most thoroughly investigated material. Combining results from numerous studies has allowed for the generation of a "phase diagram" for nanostructuring of CaF₂ in dependence of ion beam parameters. This paves the way for a first unified picture, as implications from this phase diagram should be applicable to similar materials as well.