Oxygen surfactant-assisted growth and dewetting of Co films on O-3 × 3/W(111)

Abstract

Following the cyclic heating in oxygen and annealing, an oxygen-induced 3 Â 3 reconstruction was found on the W(111) surface. The growth, crystalline structure, thermal stability, and magnetism of Co ultrathin films deposited on the O-3 Â 3/W(111) surface were investigated. The Auger signal of the oxygen was always observable and nearly invariant after either Co deposition or annealing, indicating the role of the surfactant played by oxygen. Auger electron spectroscopy and scanning tunneling microscopy measurements revealed the 2-dimensional growth of Co on O-3 Â 3/W(111). Following the annealing procedures, the surfactant oxygen was always observed to float on the film surface while the Co film transformed to 3-dimensional islands with a wetting layer. In contrast to the thermodynamically stable wetting layer of 1 physical monolayer (PML) Co on clean W(111) between 700 and 1000 K, the oxygen surfactant led to a reduction of the wetting layer to %1/3 PML after thermal annealing. The 6 and 9.6 PML Co/O-3 Â 3/W(111) revealed a stable in-plane magnetic anisotropy. A 6-fold symmetry corresponding to the crystalline structure was observed in the in-plane angle-dependent magneto-optical Kerr effect measurement. V

Mesoscopic organization of cobalt thin films on clean and oxygen-saturated Fe(001) surfaces

“…Theoretical and experimental efforts have highlighted a rich phenomenology of adsorbate-induced effects, such as modifications of the work function [1,2] or surface electronic structure [3,4], enhanced [5][6][7] or tailored [8][9][10][11][12][13][14] surface magnetism, and structural relaxations [15][16][17][18], just to name a few. Aside from the above-mentioned phenomena, a widely investigated topic is the so-called surfactant-assisted epitaxial growth [19][20][21][22][23][24]. In this case, a monolayer (or less) of foreign atoms adsorbed on the substrate before film deposition strongly influences the film morphology, both for heteroepitaxy and homoepitaxy.…”