Impacts of GeV heavy ions in amorphous metallic alloys investigated by near-field scanning microscopy

The modifications of the surface topography of amorphous metallic alloys irradiated with swift heavy ions are for the first time studied by near-field microscopy techniques. Irradiations with Pb or U ions (high (dE/d(x))(e) values) lead to the formation of hillocks surrounded by hollows, whereas no visible modifications of the specimen surface is observed after irradiation with Kr ions (low (dE/dx)(e) value). The formation of hillocks can be ascribed to the damage created in individual ion tracks, while hollows would be linked to the occurrence of the anisotropic-growth phenomenon. Both processes are induced by severe electronic excitation in the wake of incident ions.