Erratum: “Controlling acoustic waves using magnetoelastic Fano resonances” [Appl. Phys. Lett. 115, 082403 (2019)]

This is the final version. Available from AIP Publishing via the DOI in this recordThe article to which this is the erratum is available in ORE: http://hdl.handle.net/10871/3814

Hybrid magnetoacoustic metamaterials for ultrasound control

This is the author accepted manuscript. the final version is available from the American Institute of Physics via the DOI in this recordData availability: The data that support the findings of this study are available within the article and its supplementary material.We propose a class of metamaterials in which the propagation of acoustic waves is controlled magnetically through magnetoelastic coupling. The metamaterials are formed by a periodic array of thin magnetic layers ("resonators") embedded in a nonmagnetic matrix. Acoustic waves carrying energy through the structure hybridize with the magnetic modes of the resonators ("Fano resonance"). This leads to a rich set of effects, enhanced by Bragg scattering and being most pronounced when the magnetic resonance frequency is close to or lies within acoustic bandgaps. The acoustic reflection from the structure exhibits magnetically induced transparency and Borrmann effect. Our analysis shows that the combined effect of the Bragg scattering and Fano resonance may overcome the magnetic damping, ubiquitous in realistic systems. This paves a route toward the application of such structures in wave computing and signal processing.Engineering and Physical Sciences Research Council (EPSRC)European Union Horizon 202

Resonant scattering of surface acoustic waves by arrays of magnetic stripes

Owing to magnetoelastic coupling, surface acoustic waves (SAWs) may be scattered resonantly by magnetic elements, such as nickel stripes. The scattering may be further enhanced via the Borrmann effect when the elements are organized into an array that matches the acoustic wavelength. We use finite-element modeling to consider single- and double-layer stripes patterned on top of a lithium niobate surface that carries Love surface waves. We do observe enhancement in the coupling for single-layer stripes, but only for Gilbert damping below its realistic value. For double-layered stripes, a weak yet clear and distinct signature of Bragg reflection is identified far away from the acoustic band edge, even for a realistic damping value. Double-layered stripes also offer better magnetic tunability when their magnetic period is different from the periodicity of elastic properties of the structure because of staggered magnetization patterns. The results pave the way for the design of magnetoacoustic metamaterials with an enhanced coupling between propagating SAWs and local magnetic resonances and for the development of reconfigurable SAW-based circuitry

Ultrafast time-evolution of chiral Néel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.Code availability: The code that supports the findings of this study is available from the corresponding author upon reasonable request.Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows for the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions among others. We report here on the behavior of chiral DWs at ultrashort timescale after optical pumping in perpendicularly magnetized asymmetric multilayers. The magnetization dynamics is probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously varying spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of spins from the interior of the neighboring magnetic domains. We identify this time-varying change of the DW texture shortly after the laser pulse as a distortion of the homochiral Néel shape toward a transient mixed Bloch-Néel-Bloch texture along a direction transverse to the DW.LAG-ERA SographMEMAgence Nationale de la Recherche, FranceEuropean Union Horizon 2020CNRS-MOMENTUMEngineering and Physical Sciences Research Council (EPSRC