Decoration of swift heavy ion tracks in nickel-oxide with gold atoms

Abstract

We have investigated the swift heavy ion beam induced relocation of Au marker layers in NiO. It was found that, above a certain threshold value, the electronic energy deposition results in gettering of the nearby Au atoms into the latest excited ion track. In that way a continuous Au redistribution from a recent track into a new one occurs. For Kr-ions only short and partly segmented Au-containing cylinders of about 5 nm in diameter are found, which are symmetrically located around the initial marker plane. In beam direction the laterally averaged Au distribution shows a slight broadening, which saturates at relatively low fluences. In case of Xe- and Au-ions coherent cylindrical Au-decorated zones are formed which reach up to the surface, and which obviously allow for transversal Au transport towards the surface and for segregation of the Au in spherical nano-particles on top of the surface. The transversal transport mechanism is not of diffusion-like nature, but most probably by pressure induced viscous flow in the molten ion track.