Nanostructuring of strontium titanate by highly energetic ions induced plasma

Highly energetic heavy ions are efficient tool in surface nanostructuring of various materials. The irradiation of strontium titanate with GeV xenon ions leads to the creation of surface nanohillocks, where each hillock is produced by single ion impact. We focus on the creation mechanism of the nano-sized hillocks by presenting a new approach, which is based on the ability of the ion-induced strong electronic excitations in forming localized plasma. The creation of nano-plasma leads to the existence of nonlinear ion-acoustic mode that propagates in the plasma as an indicator to the feature of the nanohillocks. The solution of the plasma hydrodynamic equations shows a bell-shape relation between the normalized electron number density and distance along the crystal. The similarity to the hillock profile implies the importance of electron density in producing the observed surface structures. Furthermore, the utilized model explains the creation mechanism of hillocks-like structures in case of normal incidence as well as grazing incidence of highly energetic heavy ions.