Semiconductor-half metal transition at the Fe3O4(001) surface upon hydrogen adsorption

The adsorption of H on the magnetite (001) surface was studied with photoemission spectroscopies, scanning tunneling microscopy, and density-functional theory. At saturation coverage the insulating (root 2 x root 2)R45 degrees reconstruction is lifted and the surface undergoes a semiconductor-half metal transition. This transition involves subtle changes in the local geometric structure linked to an enrichment of Fe2+ cations at the surface. The ability to manipulate the electronic properties by surface engineering has important implications for magnetite-based spintronic devices