Recovery of the half-metallicity of anFe3O4(100)surface by atomic hydrogen adsorption

Abstract

We report experimental evidence that hydrogen termination largely enhances the spin polarization of an ${\text{Fe}}_{3}{\text{O}}_{4}(100)$ surface. An in situ prepared ${\text{Fe}}_{3}{\text{O}}_{4}(100)/\text{MgO}(100)$ 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 $<5\mathrm{%}$ to $>50\mathrm{%}$ 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.