H-induced plastic deformation of Gd thin films studied by STM

Surface modification of thin Gd films during hydrogen absorption has been i nvestigated an the nanometer scale by scanning tunneling microscopy. Two di fferent types of surface pattern appear that can be attributed to hydrogen- induced plastic deformation processes within the Gd film. Disklike islands are formed first due to GdH2 precipitation and concomitant emission of extr insic dislocation loops. At a later stage ramps appear on the surface as a result of glide displacements originating from misfit dislocations at the i nterface between the substrate and the thin film.