Magnetism and Electronic Structure of the Fe3O4(111) Surface

The magnetic and electronic structures of the Fe3O4(111) surface were investigated by conversion electron Mssbauer spectroscopy (CEMS) and ultraviolet photoemission spectroscopy (UPS), respectively. The CEMS results indicated that the Fe3O4(111) surface is covered by closure domains, and that the magnetization direction of the Fe(B) site is more parallel to the surface than the non-perpendicular easy axes while that of the Fe(A) site corresponds to the easy exes. This indicates that the spins of the Fe (A) and Fe (B) sites are non-collinear near the surface. By using UPS, we have discovered that the H atom adsorption on the Fe(A)-terminated Fe3O4(111) surface reduces the work function but does not induce charge transfer. On the O2-exposed Fe(A)-terminated Fe3O4(111) surface, on the other hand, H adsorption increases the Fe(B) t2g derived peak in the UPS spectrum and decreases the work function. This indicates that, on the O2exposed Fe(A)-terminated Fe3O4(111) surface, H atoms adsorb as cations and dope electrons to the Fe(B) t2g orbital.