Dynamics in sub-monolayer Fe-films

Abstract The properties of thin films are directly connected with the atomic structure. At elevated temperatures this structure is determined by atomic dynamics. Pronounced effects are expected for thin films of low coverage. We have investigated electronic and dynamical properties of a submonolayer Fe film on a W(1 1 0) substrate with nuclear resonance scattering (NRS) in grazing-incidence geometry. This atomistic technique is best suited for such investigations due to its element (isotopic) and submonolayer sensitivity as demonstrated in the model system of Fe/W(1 1 0). A simple relaxation model was used to explain the temperature dependence of the NRS spectra. The relaxation rates and diffusion coefficients have been calculated

Determination of The Diffusion Mechanism by A Method with New Possibilities: Nuclear Scattering of Synchrotron Radiation

ABSTRACTThe elementary diffusion jump in crystalline solids can be determined by methods derived from nuclear physics. With these methods not only diffusion rate(s) but also diffusion vector(s), i.e. the complete diffusion mechanism can be deduced. We report on a new method for probing the elementary diffusion jumps in crystalline lattices on an atomistic scale and demonstrate its potential by a study of 57Fe diffusion in different intermetallic alloys. Compared to the results of conventional tracer (macroscopic) technique, the new method provides clear and doubtless statements concerning the direction and distance of elementary jumps. One can also determine (though less precisely than with tracer diffusion), iron diffusion coefficients.</jats:p