Growth of uniform cobalt nano magnetic dots on titanum dioxide surface

Abstract

This research investigated the growth of cobalt magnetic nanodots on the rutile TiO2 (110) surface. Well ordered TiO2 (110) surface was prepared in the Ultra High Vacuum (UHV) via Ar+ sputtering and annealing. Co was deposited in-situ by Molecular Beam Epitaxy (MBE). Characterization of the growth was performed in-situ by a Variable Temperature Scanning Tunneling Microscope (VT-STM). The TiO2 (110) surface was proven to promote the Volmer-Weber growth of Co nanodots. The cobalt atoms formed small clusters at the stage of initial growth. As the coverage increased, the size and density of clusters increased. It was discovered that there existed a stable dot size, especially after a delicate post-annealing. Statistical analysis showed the stable size of nanodots was 4.0 ± 0.5 nm. The existence of the stable dot size was supported theoretically based on jellium model. An optimal set of fabrication parameters was established for the uniform magnetic nanodot growth.