The (0 0 1) surface and morphology of thin Fe3O4 layers grown by O2-assisted molecular beam epitaxy

Structure, charge distribution, and electron hopping dynamics in magnetite (Fe3O4) (100) surfaces from first principles

“…In principle, at environmentally relevant conditions, the degree of reductive adsorption that occurs on a given magnetite surface varies directly as a function of Fe 2+ availability, which ultimately depends upon both the arrangement of atoms at the surface and the rate at which electrons can migrate through the structure to surface sites. The structure of magnetite (1 0 0) has been reasonably well studied to date, with a ( p 2 Â p 2)R45°reconstruction observed most commonly following annealing under vacuum conditions (Fujii et al, 1990(Fujii et al, , 1994Shvets et al, 1992Shvets et al, , 2004Wiesendanger et al, 1992a,b;Coey et al, 1993;Tarrach et al, 1993;Voogt et al, 1995;Gaines et al, 1997;Kim et al, 1997;Chambers and Joyce, 1999;Peden et al, 1999;Seoighe et al, 1999;Stanka et al, 2000;Mijiritskii and Boerma, 2001;Mariotto et al, 2002;Ceballos et al, 2004;Spiridis et al, 2004;Fonin et al, 2005;Jordan et al, 2005Jordan et al, , 2006aPentcheva et al, 2005Pentcheva et al, , 2008Subagyo et al, 2005;Wang et al, 2006;Stoltz et al, 2008). This reconstruction can be achieved by removing half a layer of Fe tet (A-type), or by introducing oxygen defects in an Fe oct -terminated layer (B-type); the latter can also be stabilized without oxygen defects by inducing a distortion (i.e., Jahn-Teller wave) to the surface Fe oct chains Fonin et al, 2005;Pentcheva et al, 2005Pentcheva et al, , 2008.…”

Fe3O4(001)films onFe(001): Termination and recons

“…[9][10][11][12][13][14][15] The surface is usually discussed as being composed of atomic sublayers, containing either only tetrahedral iron ions Fe͑A͒ ͑the so-called A layer͒ or oxygen and octahedral iron ions Fe͑B͒ ͑the so-called B layer͒. The distance between A or B layers is about 2.1 Å, whereas the smallest interlayer ͑A-B͒ spacing is about 1.1 Å.…”

“…Neither A nor B bulk termination of the Fe 3 O 4 ͑001͒ surface is chargecompensated, and a number of models assume that the charge neutrality condition is a driving force behind the reconstruction. The obvious way to achieve the autocompensated Fe 3 O 4 ͑001͒ surface with the observed reconstruction is to remove certain surface atoms: half of the Fe 3+ ions for the A termination [10][11][12]14 or a number of oxygens for the B termination. 10,13 However, surface stability can be achieved also through electronic degrees of freedom.…”

Fe3O4 thin films: controlling and manipulating an elusive quantum material

“…While thousands of studies have been devoted to try to understand the first order Verwey transition in magnetite, the high Curie temperature (T C ∼ 860 K) and the half-metallic character of Fe 3 O 4 as predicted by band theory [1,2] have triggered considerable research efforts world wide to make this material suitable for spintronic applications in the form of thin film devices [3,4,5,6,7]. Using a variety of deposition methods, epitaxial growth on a number of substrates has been achieved [5,6,7,8]. Yet, it is remarkable that in the twenty years of research on Fe 3 O 4 thin films, the first order Verwey transition [9] in thin films is always broad [6,7,10,11,12,13].…”