Scanning tunneling spectroscopy of individual iron atoms on a permalloy surface

The topographic and electronic structure of 10-20-nm-thick permalloy films has been investigated under ultrahigh vacuum conditions. The films were characterized using scanning tunneling microscopy/spectroscopy. Permalloy grows as a polycrystalline film. The size of the crystallites is in the range of 5-20 nm for the permalloy films. The spectroscopic data show a distinct minority electron state, which can be assigned to the presence of iron in the permalloy surface. It was found that the state not only decays but also shifts in position when moving the STM tip away from the center position of the iron atoms.