Growth and oxidation of vanadium ultra-thin buffer layers on Fe(001)

The growth and oxidation of vanadium ultra-thin films deposited on Fe(001) have been investigated by combining scanning tunneling microscopy and Auger electron spectroscopy. In the early stages of growth, vanadium develops a structure pseudomorphic to the Fe(001) substrate, nucleating one-layer-thick islands. At higher coverages, the growth proceeds nearly layer-by-layer, up to a thickness of about 5 atomic layers. Upon oxygen exposure, the vanadium film gets oxidized, while no signatures of the formation of iron oxides are detected in Auger spectra. As revealed by scanning tunneling microscopy images, the oxidation increases the surface roughness, suggesting the formation of an amorphous vanadium oxide layer.