Investigation Of STM Tip-induced Atomic Manipulation On Metal Substrates

We investigate the Scanning Tunneling Microscopy (STM) tip-mediated atomicmotion on top of islands and interlayer mass transport at island edges based on MolecularStatic (MS) method. Our results show that STM manipulation has an important effect onCo atomic diffusion on top of Co islands on a Cu(001) substrate and at the island edge.The interaction between the STM tip and the adatom as well as the strong shapetransitions in the island and in the substrate result in the change of the jump diffusionbarrier on top of the island, Ehrlich-Schwoebel(ES) and exchange barrier at the islandedge. It is found that the diffusion barrier of the above three diffusion processes can bedecreased by adjusting the distance between the tip and the substrate.A STM manipulation scheme for a controlled single atom transport is demonstrated.Atomic-scale simulations are performed to study the vertical and lateral manipulations ofa single Co adatom on a Cu(111) surface and on a Cu(554) surface or at the step using aSTM tip. It is found that the stacking sequence of tip structure, atomic manipulation modeand the surface type have the effect on the atomic manipulation process. It is revealed thatthe adsorbed Co atom can be extracted from the flat Cu(111) or the stepped Cu(554)surface in vertical manipulation processes by the Cu29STM tip. By using lateralmanipulation one can unload the extracted Co adatom at the step on the Cu(554) surface.The possibilities and mechanisms of extracting and unloading single adatoms on metalsurfaces with a STM tip at zero bias voltage are explored. A Co atomic chain can also bemanufactured with the same atomic manipulation.