Size-dependent quantum diffusion of Gd atoms within Fe nano-corrals

We systematically studied the size-dependent quantum diffusion of Gd atoms within Fe circular quantum corrals on Ag(111). By varying the size of the quantum corrals, different types of patterns are observed inside the corrals, including a single dot and circular orbits for the diffusion of Gd adatoms. In addition, the motion of the adatoms also forms circular-like orbits outside the corral. Via quantitative analysis, we confirm that the regions with adatoms' high visiting probability are consistent with the positions of the local electronic density-of-states maxima, both inside and outside the corrals within a <0.2nm offset. The results agree well with kinetic Monte Carlo simulations that utilize the experimentally determined interaction between Gd and Fe circular corrals. These findings demonstrate that one can engineer adatom motion by controlling the size of the quantum corrals.