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Isotropic transmission of magnon spin information without a magnetic field

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Science Advances  21 Jul 2017:
Vol. 3, no. 7, e1700638
DOI: 10.1126/sciadv.1700638
  • Fig. 1 Experimental configuration and device architecture.

    (A) Schematic of the experimental configuration. A laser beam is focused using a 100× objective onto the sample, which is placed on top of a nanopositioning stage, and the scattered beam is collected by the same objective and directed toward an interferometer by using a polarizing beam splitter. A white light and a camera are collinearly arranged for positioning and stabilization of the sample. Spin waves were excited by a GSG-type stripe antenna, which is shown to be connected to an RF signal generator. The enlarged view of the device shows the direction of the RF current (Irf) and RF field (Hrf). Instruments that are controlled by the computer are each marked by an asterisk. N.A., numerical aperture. (B) Schematic of the sample cross section showing the Cr(5)/Cu(10)/Pd(5)/[Co(0.3)/Pd(1.1)]6/Py(5) ≡ Co-Pd-Py multilayer structure of the microconduits. The numbers in the first brackets indicate thickness in nm. Two reference microconduits consisting of Cr(5)/Cu(10)/Pd(5)/[Co(0.3)/Pd(1.1)]6 ≡ Co-Pd and Cr(5)/Py(5) ≡ Py are also shown.

  • Fig. 2 Device characterization.

    MOKE hysteresis loops for the microconduits (squares) (A) Co-Pd-Py in out-of-plane configuration, (B) Co-Pd in out-of-plane configuration, and (C) Py in in-plane configuration. a.u., arbitrary units. Direction of the applied field (Ha) are shown by arrows for the three different microconduits. Dotted lines represent the hysteresis loop for a continuous film of the corresponding microconduit.

  • Fig. 3 Spin-wave channeling in straight microconduits.

    (A to C) CCD camera images of the three devices, the Co-Pd-Py, Co-Pd, and Py microconduits, showing the laser position where the BLS spectra were recorded. Remanent magnetization directions are indicated by arrows. (D to F) BLS spectra (circles) as a function of RF for the three devices at remanence. The spectra were compared with the noise floor (squares) obtained without RF excitation. (G) Two-dimensional spin-wave intensity maps overlaid on SEM images of the Co-Pd-Py microconduit at 3.3, 4.2, and 5.6 GHz recorded over an area of 3 × 2 μm2. Each pixel corresponds to BLS intensity at that position. (H) Dependence of BLS integral intensity (squares) on the propagation coordinate for the three different modes at 3.3, 4.2, and 5.6 GHz along the center of the Co-Pd-Py microconduit. Lines refer to the fit to the experimental data using an exponential function, as discussed in the text.

  • Fig. 4 Isotropic spin-wave flow.

    (A) SEM image of the concept device in which a Co-Pd-Py conduit has three channels at three different angles. Antenna is placed at the three-channel junction. (B) BLS spectra as a function RF recorded at three channels indicated by different symbols in the SEM image. (C) Two-dimensional spin wave intensity maps at 5.7, 6.7, and 8.2 GHz recorded over an area of 3 × 12 μm2. Each pixel corresponds to BLS intensity at that position.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1700638/DC1

    fig. S1. Width dependence of magnetic hysteresis in Co-Pd-Py microconduits.

    fig. S2. BV spin waves in a Py microconduit.

    fig. S3. DE spin waves in Co-Pd-Py and Py microconduits.

    fig. S4. Effect of far-field excitation by the antenna.

    fig. S5. Width dependence of spin wave spectrum in Co-Pd-Py microconduits.

    fig. S6. Anisotropic propagation of spin waves when magnetized in-plane.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Width dependence of magnetic hysteresis in Co-Pd-Py microconduits.
    • fig. S2. BV spin waves in a Py microconduit.
    • fig. S3. DE spin waves in Co-Pd-Py and Py microconduits.
    • fig. S4. Effect of far-field excitation by the antenna.
    • fig. S5. Width dependence of spin-wave spectrum in Co-Pd-Py microconduits.
    • fig. S6. Anisotropic propagation of spin waves when magnetized in-plane.

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