Resonant nanodiffraction x-ray imaging reveals role of magnetic domains in complex oxide spin caloritronics

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Science Advances  02 Oct 2020:
Vol. 6, no. 40, eaba9351
DOI: 10.1126/sciadv.aba9351
  • Fig. 1 Magnetic structure of GdIG.

    (A) Atomic structure and magnetic moments in one atomic layer of the GdIG cubic unit cell, highlighting oxygen octahedra and tetrahedra. Arrows indicate the directions of the magnetic moments of Gd3+ ions (red) and Fe ions on tetragonal (light green) and octahedral (dark green) sites. (B) Directions of the total magnetization M under the assumption of bulk-like ⟨111⟩ magnetization directions in a (001)-oriented GdIG thin film. (C) Hall bar SSE device consisting of a patterned GdIG MI and a thin Pt conductor. (D) Magnetic field hysteresis of VSSE at 20, 150, and 300 K. (E) Electric field polarization vectors for right (R)–, left (L)–, and π-polarized incident x-ray nanobeams.

  • Fig. 2 Domain imaging in GdIG SSE devices.

    (A) Optical micrograph of a patterned GdIG layer from which GdIG has been removed in the area outside the light square. X-ray nanobeam diffraction maps of (B) circular-polarization flipping ratio Fcir and (C) linear π-polarization flipping ratio Fπ in the same region. The areas of nearly uniform contrast at the edges of the images in (B) and (C) are in regions from which the GdIG layer had been removed and in which there is vanishingly low diffracted intensity.

  • Fig. 3 X-ray photon energy dependence of resonant scattering contrast.

    (A) Maps of Fcir of the same region of the GdIG layer for several photon energies near the Gd L2 resonance. (B) Predicted Fcir for four ⟨111⟩ magnetization directions. (C) Observed and predicted contrast of Fcir measured for regions of (A) with opposite values of Fcir (bottom). X-ray fluorescence intensity as a function of photon energy (top).

  • Fig. 4 Magnetic domain wall orientation and magnetic structure.

    (A) Nanobeam diffraction map of Fcir within a region of the GdIG pattern with large magnetic domains. The footprint of the incident and diffracted x-ray beams is horizontal. The nearly uniform contrast at the edges of the image in (A) is in regions from which the GdIG layer had been removed. (B) Schematic of the in-plane projection of the magnetization of the domains. The edges of the patterned GdIG layer are indicated by dashed lines.

  • Fig. 5 Interaction between crystallographic and magnetic microstructure.

    (A) Nanobeam diffraction maps of Fcir at micrometer length scales. The in-plane crystallographic directions are shown in the diagram below the images. (B) Crystallographic tilt toward the [010] (vertical) direction. (C) Integrated diffracted x-ray intensity at the 008 Bragg reflection. The magnetic response to the structural variation in (B) and (C) competes with the development of facets along directions of the lowest domain boundary energy.

Supplementary Materials

  • Supplementary Materials

    Resonant nanodiffraction x-ray imaging reveals role of magnetic domains in complex oxide spin caloritronics

    Paul G. Evans, Samuel D. Marks, Stephan Geprägs, Maxim Dietlein, Yves Joly, Minyi Dai, Jiamian Hu, Laurence Bouchenoire, Paul B. J. Thompson, Tobias U. Schülli, Marie-Ingrid Richard, Rudolf Gross, Dina Carbone, Danny Mannix

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