The (100) surface of magnetic γ′-Fe4N films epitaxially grown on Cu(100) showed a (2 x 2)p4gm reconstruction. The atom positions determined experimentally were properly accounted for by first-principles total energy calculations, which further reveal that the (2 x 2)p4gm reconstruction requires the topmost Fe4N2 plane to be magnetic and effectively decoupled from the rest of the crystal and that it originated from the perpendicular crossing of one-dimensionally dimerized Fe chains.

1D Lattice Distortions as the Origin of the (2 x 2)p4gm Reconstruction in γ′-Fe4N(100) - a Magnetism-Induced Surface Reconstruction. J.M.Gallego, D.O.Boerma, R.Miranda, F.Ynduráin: Physical Review Letters, 2005, 95[13], 136102 (4pp)