AVS 52nd International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI-ThA

Paper MI-ThA3
MBE Growth of Epitaxial Co@sub2@MnGe on SrTiO@sub3@ (001) and MgO (001) Substrates

Thursday, November 3, 2005, 2:40 pm, Room 204

Session: Magnetic Oxides
Presenter: S.K. Srivastava, University of Minnesota
Authors: S.K. Srivastava, University of Minnesota
C. Adelmann, University of Minnesota
X. Dong, University of Minnesota
D. Schlom, Penn State University
C. Ahn, Yale University
C.J. Palmstrom, University of Minnesota
Correspondent: Click to Email
The combination of metallic ferromagnetic Heusler alloys with metal oxides can be used for the formation of multifunctional material heterostructures. The growth of Co@sub2@MnGe with a 45° in-plane rotation results in a lattice mismatch of -3.84% and +3.82% for SrTiO@sub3@ (001) and MgO (001), respectively. Etching of SrTiO@sub3@, followed by ex-situ annealing in O@sub2@ (~1 atm) at 1223K for 1 hour was used to form a TiO@sub2@ terminated surface@footnote 1@ with straight edged steps. AFM shows terraces with step heights on the order of one unit cell (~ 4Å) and LEED images show a (@sr@5x@sr@5)R26.6° superstructure. The growth of Co@sub2@MnGe was initiated by growing alternating atomic layers of MnGe and Co in an MBE system at 298K to promote wetting of the substrate and the desired (001) atomic stacking sequence. Following the growth of 20 atomic layers, the film was annealed in-situ at 673K for 1 hour. The remaining 250Å Co@sub2@MnGe film was grown by codeposition at 723K and annealed at 823K for 1 hour. RHEED and LEED images from the Co@sub2@MnGe films showed (2x2) reconstruction. For growth on MgO, the substrates were cleaned and annealed ex-situ in O@sub2@ (~1 atm) at 1273K for 2 hours giving a (1x1) RHEED pattern. A growth scheme similar to the one mentioned above was used for the growth of Co@sub2@MnGe on MgO and resulted in a (2x2) RHEED pattern. XRD is consistent with the single crystal epitaxial growth of Co@sub2@MnGe films on SrTiO@sub3@ and MgO, with out-of-plane lattice parameters of 5.745Å and 5.758Å, respectively. Both films are ferromagnetic with no significant in-plane magnetic anisotropy as measured by VSM. This presentation will emphasize the effect of pre-treatment and deposition sequence on the structural and magnetic properties of Heusler alloy films grown on oxide substrates. Supported by ONR-MURI. @FootnoteText@ @footnote 1@G.Koster, B.L.Kropman, G.J.H.M.Rjinders, D.H.A.Blank and H.Rogalla, Appl. Phy. Lett., 73, 2920 (1998).