Initial stage of silver overlayer formation on the Ni(110) surface

Abstract

Silver-induced surface atomic structures on a Ni(110) surface up to 1 ML between room temperature and 673 K were studied using ultrahigh vacuum scanning tunneling microscopy and low-energy electron diffraction. A 0.72 ML-Ag-deposited surface at room temperature showed monolayer-high aggregated Ag stripes separated by periodic trenches and shallow troughs. Ag stripes consisted of six aggregated Ag atoms in the $\left[1\bar{1}0\right]$ direction to form a one-dimensional (1-D) cluster and it extended in the $\left[001\right]$ direction with 3 × 9 and $\left(\begin{array}{cc}3& 0\\ \pm 1& 9\end{array}\right)$ surface superstructures. Some Ag stripes were bridged by fuzzy regions where 1-D fluctuating Ag atoms were adsorbed on the substrate Ni(110) row. Above 473 K, the 1-D Ag cluster consisting of seven atoms formed Ag stripes with $12\times$ periodicity of the surface unit cell in the $\left[1\bar{1}0\right]$ direction, and the Ni(110) substrate surface was exposed between the Ag stripes. The stability of the Ag stripes was confirmed by conducting first principles calculations and through simulated STM images.