Research ArticleAPPLIED PHYSICS

Nonreciprocal surface acoustic wave propagation via magneto-rotation coupling

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Science Advances  07 Aug 2020:
Vol. 6, no. 32, eabb1724
DOI: 10.1126/sciadv.abb1724
  • Fig. 1 Schematics of the magneto-rotation coupling.

    Depending on the propagation direction, SAWs rotate the lattice in opposite directions (as indicted by the blue and red oriented cycles in the figure). This rotational motion couples with the magnetization via magnetic anisotropies, giving rise to a circularly polarized effective field, which either suppresses or enhances the magnetization precession (purple cone), and, in turn, induces a nonreciprocal attenuation on the SAWs.

  • Fig. 2 Nonreciprocal propagation of acoustomagnetic waves in Ta/CoFeB/MgO.

    (A) Device schematics of SAWs coupling to an FM layer at gigahertz frequencies. (B) Attenuation of acoustic waves, P±k, near a spin-wave resonance condition for SAW numbers +k and −k. arb. units, arbitrary units.

  • Fig. 3 Dependence of the NR ratio on the magnetic field direction.

    The magnetic field direction is varied with respect to the SAW propagation directionxˆ. We observe a strong variation of the NR ratio, reaching a maximum value of 100% at ϕ = 184(see the inset).

  • Fig. 4 Assessment of Dzyaloshinskii-Moriya interaction by nonreciprocal magnon-phonon interaction.

    (A) Resonance field difference ΔHres between acoustomagnetic waves was induced by SAWs propagating in +k and −k. (B) Angle dependence of the resonance field difference between acoustomagnetic waves induced by SAWs with wave numbers +k and −k fitted according to Eq. 2.

Supplementary Materials

  • Supplementary Materials

    Nonreciprocal surface acoustic wave propagation via magneto-rotation coupling

    Mingran Xu, Kei Yamamoto, Jorge Puebla, Korbinian Baumgaertl, Bivas Rana, Katsuya Miura, Hiromasa Takahashi, Dirk Grundler, Sadamichi Maekawa, Yoshichika Otani

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