In SituMössbauer Analysis of Hyperfine Interactions near Fe(110) Surfaces and Interfaces

Hyperfine interaction parameters near clean and Ag-covered Fe(110) surfaces could be measured for the first time, for the first and the second monolayer separately, by means of in situ conversion-electron Mössbauer spectroscopy of oligatomic Fe(110) films on W(110) with monolayer ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ probes. Quadrupole splitting deviates strongly from zero in the topmost monolayer only, indicating the reduced symmetry; it can be used to measure first- to second-layer self-diffusion. Magnetic hyperfine fields provide information on magnetic order near the surface with monolayer resolution.