Research ArticleELECTROMAGNETISM

Interface-driven topological Hall effect in SrRuO3-SrIrO3 bilayer

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Science Advances  08 Jul 2016:
Vol. 2, no. 7, e1600304
DOI: 10.1126/sciadv.1600304
  • Fig. 1 Structure and basic physical properties of the SrRuO3-SrIrO3 bilayers.

    (A) Temperature (T) dependence of resistivity (ρ, top panel), MR (middle panel), and out-of-plane magnetization measured at 0.05 T (bottom panel) for the (SrRuO3)m-(SrIrO3)2 bilayers (m = 4, 5, 6, and 7). (B) Schematics of Bloch- and Néel-type skyrmions. (C) Schematics and an atomically resolved HAADF-STEM image of the studied bilayer structure. In the STEM image, SrTiO3 is capped on top of the SrIrO3 layer to protect the surface from electron beam radiation. uc, unit cells. (D) Anomalous Hall conductance (σHA) as a function of magnetization (M), which was varied through temperature.

  • Fig. 2 Hall resistivity of all the bilayers.

    (A) Magnetic field dependence of Hall resistivity (ρH) of the (SrRuO3)m-(SrIrO3)2 bilayers (m = 4, 5, 6, and 7) at various temperatures. Red and blue represent sweep directions of magnetic field. Ordinary Hall term is subtracted by the linear fitting in a higher magnetic field region. (B) Detailed view of the Hall resistivity of m = 5. (C) Contribution from AHE and THE of m = 5 at 80 K (see text for details). (D) Color map of topological Hall resistivity in the T-H plane for m = 5. Black open and filled symbols represent coercive field (Hc) and the field at which topological Hall resistivity reaches its maximum (Hp), respectively.

  • Fig. 3 THE and calculated stability of skyrmions as a function of the ferromagnet thickness.

    (A) Topological Hall resistivity as functions of m and T.TC of the bilayers is also shown. The schematics below indicate the relationship between the spin structure and interface DM interaction depending on SrRuO3 thickness. (B) m dependence of the ordinary Hall coefficient (R0, top panel), the maximum of the topological Hall resistivity in the T-H plane [ρHT(m), middle panel], and the inverse of the square root of the possible skyrmion density (nsk−1/2, bottom panel). (C) Calculated phase diagram of the stable magnetic structures as functions of m and D. We have obtained three types of the magnetic structures, namely, helix, skyrmion, and perfect ferromagnet. For the former two, we also show the typical real-space patterns in the right panel. The image size is 150 × 150 unit cells.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/7/e1600304/DC1

    section SI. Comparison between the Kerr rotation angle and the magnetization

    section SII. Details of the calculation of the skyrmion stability in the multilayer

    section SIII. Preliminary magnetic force microscopy images

    fig. S1. Kerr rotation, magnetization, and topological Hall resistivity.

    fig. S2. Multilayer model and calculated skyrmion radius.

    fig. S3. Magnetic force microscopy images for m = 5 measured at 50 K and various magnetic field.

  • Supplementary Materials

    This PDF file includes:

    • section SI. Comparison between the Kerr rotation angle and the magnetization
    • section SII. Details of the calculation of the skyrmion stability in the multilayer
    • section SIII. Preliminary magnetic force microscopy images
    • fig. S1. Kerr rotation, magnetization, and topological Hall resistivity.
    • fig. S2. Multilayer model and calculated skyrmion radius.
    • fig. S3. Magnetic force microscopy images for m = 5 measured at 50 K and various magnetic field.

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