Translational Manipulation of Magnetic Cobalt Adatoms on the Si(100)‑2 × 1 Surface at 9 K

The controlled motion of magnetic impurities on semiconductor (SC) surfaces is of crucial importance for atomic scale magnetic devices. Still challenging because of their strong reactivity with SCs, magnetic impurities are usually studied in bulk SCs, thus preventing their manipulation. Here, we show that a single Co adatom can be steadied on the bare Si(100)-2 × 1 surface in a pedestal configuration at low temperature, 9 K, and moved along the reconstructed silicon dimer rows via the use of a scanning tunneling microscope. The electronic characteristics of the Co adatom and its surroundings are investigated via topography and dI/dV measurements. Our findings reveal that the Si–Co bonding involves hybridization between the Si-p and the Co-p_xp_y orbitals. This configuration indicates that the Co-d orbitals remain weakly hybridized with the silicon atoms. These results are supported by density functional theory calculations where the role of the As dopant is discussed as well as the surface reconstruction. Therefore, we show that the motion direction of the Co adatom can be influenced by the surrounding c(4 × 2) or p(2 × 2) surface reconstruction phases, thus opening future interesting magnetic applications.