Half-metallicity induced by boron adsorption on an Fe3O4(100) surface

The spin polarization of magnetite Fe3O4 is significantly reduced at its surfaces, which is unfavorable for the development of spintronic devices based on this material. In order to enhance the surface spin polarization, the Fe3O4(100) surface is modified here through the adsorption of boron (B) atoms and investigated using density functional theory (DFT) calculations. We find for the bulk-terminated and cation-redistributed surfaces that a band gap is opened in the spin-up electronic states due to the formation of a strong bond between the B atom and a surface oxygen atom, i.e., B adsorption induces half-metallicity at the Fe3O4(100) surface. Besides the surface Fe and O atoms, the adsorbed B atoms have a considerable density of -100% spin-polarized electronic states at the Fermi level, which might provide a means of improving the efficiency of spin injection into spintronic devices.