Research ArticleSTRAIN ENGINEERING

Role of scaffold network in controlling strain and functionalities of nanocomposite films

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Science Advances  10 Jun 2016:
Vol. 2, no. 6, e1600245
DOI: 10.1126/sciadv.1600245
  • Fig. 1 Microstructure of nanoscaffolding films.

    (A) Cross-section STEM image showing the alternating growth of LSMO (white) and MgO vertical nanoscaffolds (dark) on STO (001) substrates. Inset: Plan-view STEM image of the LSMO:MgO films with 22% MgO phase, which shows the MgO nanoscaffolds, with a feature size of ~4 nm, in the LSMO matrix. (B) High-resolution STEM image showing the vertical MgO nanoscaffolds in LSMO phase. The red arrows point out MgO nanoscaffolds. (C) Zoomed-in yellow box area in (B) showing the film-substrate interface. One unit cell of LSMO transition layer is formed between nanocomposite film and substrate. (D) High-resolution STEM image showing the vertical interface between the MgO and LSMO phase.

  • Fig. 2 Nanoscaffold density–dependent strain and its distribution simulated by the phase-field method.

    (A and B) RSM (002) (A) and RSM (103) (B) of 450-nm nanocomposite films with 40% MgO. (C) Relationship between the strain state in the LSMO phase and the scaffold phase volume ratio (red represents MgO, and blue curve represents ZnO). (D) Simulated out-of-plane strain in LSMO:MgO by phase-field model with and without considering misfit dislocations. Top x axis represents the circumference obtained from simulations at different MgO volumes. (E) Schematic drawing of MgO nanoscaffold in the LSMO matrix with different MgO volume ratios (from left to right: ~5, ~11, ~23, and ~41%, respectively). (F) Calculated strain distribution in the LSMO matrix and MgO nanoscaffolds in the plane marked as white dash lines in (E) for different MgO compositions (from left to right: ~5, ~11, ~23, and ~41%, respectively). The film thickness of this simulated film is 250 nm.

  • Fig. 3 Nanoscaffold density–dependent magnetic properties.

    (A) M-H loops of LSMO:MgO (15%) nanocomposite films. The inset is M-H loops of LSMO:MgO (5%) films. (B) M-H loops of LSMO:ZnO (15%) nanocomposite films. (C) R-T curves at 0 and 1 T for LSMO:ZnO (15%), LSMO:MgO (15%), and a reference LSMO film. (D) MR-T (1 T) curves for LSMO:ZnO, LSMO:MgO, and a reference LSMO film. (E) Scaffold phase volume ratio–dependent resistance at 100 K (red) and saturated magnetization (blue) at 20 K for LSMO:ZnO (15%) and LSMO:MgO (15%) films. The magnetizations have been normalized to the volume of LSMO. “Strain-induced” means that magnetization and resistance change are induced by the strain effect. “Volume-induced” means that resistance change is dominated by the volume effect. (F) Scaffold phase volume fraction–dependent MR (1 T, red) at 130 K for the LSMO:ZnO and LSMO:MgO films. The blue and green data points are MR measured under 3 and 9 T, respectively, for the LSMO:MgO films. The gray square highlights the MR measured at the same temperature but different magnetic fields.

  • Fig. 4 Nanoscaffold dimension–dependent strain and properties.

    (A) RSM (002) of 600-nm LSMO:MgO (22%) nanocomposite films grown at different temperatures (from left to right: 750°, 790°, 835°, and 900°C, respectively). (B) Plan-view TEM images of films grown at 835° and 900°C, respectively. Scale bars, 10 nm. (C) Temperature-dependent nanoscaffold feature size. (D) Growth temperature–dependent strain and MR (20 K).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/6/e1600245/DC1

    table S1. Vertical lattice strain reported in different systems with direct lattice matching.

    table S2. Vertical lattice strain reported in different systems with domain matching.

    table S3. The lattice parameters of LSMO:MgO nanoscaffolding films.

    table S4. The elastic stiffness tensor of the materials used in our work.

    fig. S1. Strain design flow in vertical nanocomposites.

    fig. S2. Microstructure of LSMO:MgO nanoscaffolding films.

    fig. S3. XRD of nanocomposites with different nanoscaffold density.

    fig. S4. Strain state evaluated by RSM.

    fig. S5. Thickness-dependent strain distribution in nanoscaffolding films.

    fig. S6. XRD of nanocomposites with different nanoscaffold size.

    fig. S7. Magnetic moments versus O-Mn-O angle by DFT calculation.

    fig. S8. The relationship between MgO cylinder surface and MgO volume.

    fig. S9. The simulated of nanoscaffolds in a matrix.

    fig. S10. The relationship between MgO cylinder surface and its radius.

    fig. S11. Critical radius and the residual vertical mismatch strain versus MgO volume.

    S1. Deriving the analytical expressions of critical thickness (hc) and radius (Rc) in vertical nanocomposite thin films

  • Supplementary Materials

    This PDF file includes:

    • table S1. Vertical lattice strain reported in different systems with direct lattice matching.
    • table S2. Vertical lattice strain reported in different systems with domain matching.
    • table S3. The lattice parameters of LSMO:MgO nanoscaffolding films.
    • table S4. The elastic stiffness tensor of the materials used in our work.
    • fig. S1. Strain design flow in vertical nanocomposites.
    • fig. S2. Microstructure of LSMO:MgO nanoscaffolding films.
    • fig. S3. XRD of nanocomposites with different nanoscaffold density.
    • fig. S4. Strain state evaluated by RSM.
    • fig. S5. Thickness-dependent strain distribution in nanoscaffolding films.
    • fig. S6. XRD of nanocomposites with different nanoscaffold size.
    • fig. S7. Magnetic moments versus O-Mn-O angle by DFT calculation.
    • fig. S8. The relationship between MgO cylinder surface and MgO volume.
    • fig. S9. The simulated of nanoscaffolds in a matrix.
    • fig. S10. The relationship between MgO cylinder surface and its radius.
    • fig. S11. Critical radius and the residual vertical mismatch strain versus MgO volume.
    • S1. Deriving the analytical expressions of critical thickness (hc) and radius (Rc) in vertical nanocomposite thin films

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