First-principles study of atomic hydrogen adsorption on Fe3O4(100)

The adsorption of atomic hydrogen on an Fe3O4(100) surface is investigated using first-principles calculations. Our calculations reveal that hydrogen atoms prefer bonding with surface oxygen atoms not with tetrahedral iron atoms. The hydrogen-adsorbed Fe3O4(100) surface can be represented by a (1 × 1) unit cell, which is consistent with our recent experimental result. The spin-up surface-state bands are found to be shifted toward the deep level due to hydrogen adsorption. As a result, a band gap appears in the spin-up electronic states and half-metal behavior occurs at the H/Fe3O4(100) surface. The transition from a metallic to half-metallic surface due to hydrogen adsorption is discussed through analysis of the calculated spin-resolved band structure and differential charge density distribution. The reason for the enhancement of the spin polarization is attributed to a donation-redistribution process by O―H bond formation but not to detailed atomic structures of Fe and O atoms such like Jahn–Teller distortion.