An investigation was made of the structural and compositional changes that were introduced by the segregation of substrate Mg to the surface of 1μ-thick (001) Fe3O4 films on (001) MgO. The surfaces of the molecular-beam epitaxially grown samples were flat, and exhibited a (v2 x v2) R45º reconstruction with respect to the Fe3O4 surface unit cell. The onset of Mg segregation to the surface occurred at about 670K; with long narrow extensions of terraces growing along the [110] and [1¯10] directions. Heating in O produced a 1 x 4 surface reconstruction, and extremely long (100nm) wide terraces. This annealing stage was attributed to the formation of a MgFe2O4 surface phase which exhibited a highly anisotropic surface diffusion and step formation energy.

J.F.Anderson, M.Kuhn, U.Diebold, K.Shaw, P.Stoyanov, D.Lind: Physical Review B, 1997, 56[15], 9902-9