AVS 50th International Symposium
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM8
Low Energy Electron Microscopy of the Quantum Electronic Structure and Stability of Ag Films on Fe(100)

Wednesday, November 5, 2003, 10:40 am, Room 327

Session: Surface and Interface Structure: Metals
Presenter: M.S. Altman, Hong Kong University of Science and Technology
Authors: K.L. Man, Hong Kong University of Science and Technology
Z.Q. Qiu, University of California at Berkeley
M.S. Altman, Hong Kong University of Science and Technology
Correspondent: Click to Email
Laterally resolved measurements of the reflected electron intensity from Ag films on the Fe(100) surface have been made with low energy electron microscopy (LEEM). Intensity peaks are observed at very low energy that are associated with quantum well resonances in the Ag film above the vacuum level. The dispersion of the quantum well peaks with increasing film thickness is well accounted for by the phase accumulation model, which has been used widely to explain the occupied quantum well states that are observed with photoemission in this and other systems. The signature quantum well peaks that are observed in electron reflectivity are then used in combination with real-space LEEM measurements to monitor film stability during annealing. We find that uniform three monolayer (ML) thick films decompose directly into spatially separated two and five ML thick film regions, whereas uniform four ML thick films decompose initially into three and five ML thick regions and eventually into two and five ML thick regions. The greater stability of two and five ML thick films has been attributed to band structure features near the zone center, which are the source of long period magnetic oscillatory coupling through Ag films. The relative stability of three and four ML thick films may be evidence that band structure features related to the neck of the Fermi surface, which give rise to the short period oscillatory coupling, also play a role in film quantum electronic stability.