Recovery of the half-metallicity of an Fe3O4(100) surface by atomic hydrogen adsorption

We report experimental evidence that hydrogen termination largely enhances the spin polarization of an Fe3O4(100) surface. An in situ prepared Fe3O4(100)/MgO(100) film surface was exposed to atomic hydrogen and its surface spin polarization (P) was monitored with a spin-polarized metastable helium-atom beam under external magnetic fields of 0-5 T. The spin asymmetry at the high-energy cutoff, which reflects P at the Fermi level of the topmost surface, increased from <5% to >50% at 298 K by H adsorption. The enhancement in P was found to be consistent with the H-induced change in the surface electronic states predicted by a density-functional theory calculation.