Functional nanostructures self-assembled on templated surfaces

Abstract

This work consists of surface studies of three systems; firstly, the growth of Fe nanoclusters on the Ge(001) surface has been studied using low-temperature scanning tunneling microscopy (STM), X-ray magnetic circular dichroism (XMCD) and density functional theory (DFT) calculations. STM results indicate that Fe nucleates on the Ge(001) surface, forming well-ordered nanoclusters of uniform size. Depending on the preparation conditions, two types of nanoclusters were observed having either four or sixteen Fe atoms within a nanocluster. The results were confirmed by DFT calculations. Annealing the nanoclusters at 420 K leads to the formation of linear nanocluster arrays, which follow the Ge dimer rows of the substrate, due to cluster mobility at such temperature. The Fe nanoclusters and nanorow structures formed on the Ge(001) surface show a superparamagnetic behaviour as measured by X-ray magnetic circular dichroism.