Magnetic Friedel Oscillation At The Fe(001) Surface: Direct Observation By Atomic-Layer-Resolved Synchrotron Radiation Fe-57 Mossbauer Spectroscopy

The surface magnetism of Fe(001) was studied in an atomic layer-by-layer fashion by using the in situ iron-57 probe layer method with a synchrotron Mossbauer source. The observed internal hyperfine field H-i(nt) exhibits a marked decrease at the surface and an oscillatory behavior with increasing depth in the individual upper four layers below the surface. The calculated layer-depth dependencies of the effective hyperfine field vertical bar H-eff vertical bar, isomer shift delta, and quadrupole shift 2 epsilon agree well with the observed experimental parameters. These results provide the first experimental evidence for the magnetic Friedel oscillations, which penetrate several layers from the Fe(001) surface.