Direct observation of coherent magnons with suboptical wavelengths in a single-crystalline ferrimagnetic insulator

Förster, Jens; Gräfe, Joachim; Bailey, Joe; Finizio, Simone; Träger, Nick; Groß, Felix; Mayr, Sina; Stoll, Hermann; Dubs, Carsten; Surzhenko, A. B.; Liebing, Niklas; Woltersdorf, Georg; Raabe, Jörg; Weigand, Markus; Schütz, Gisela; Wintz, Sebastian

doi:10.1103/physrevb.100.214416

Cited by 27 publications

(11 citation statements)

References 49 publications

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“…1, can have two "valleys" around frequency minima at finite wave numbers (which we call "U points"). Importantly, such spin waves can be not only modeled numerically (as we do here) but also detected and imaged experimentally [15,16]. This promises a direct experimental verification of the effects predicted in this paper-backscattering-induced wavelength conversion and Möbius-like confinement-and gives credibility to the proposed development of a spin-wave version of valleytronics ("magnon valleytronics").…”

Section: Introductionsupporting

confidence: 68%

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

Fripp

Kruglyak

2021

Phys. Rev. B

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We have used micromagnetic simulations to model backward-volume dipole-exchange spin waves in graded profiles of the bias magnetic field. We demonstrate spin-wave wavelength conversion upon the wave's reflection from turning points due to the two characteristic minima ("U points") occurring in their dispersion at finite (nonzero) wave vectors. As a result, backward-volume dipole-exchange spin waves confined in "spin-wave wells" either form Möbius modes, making multiple real-space turns for each reciprocal-space round trip, or split into pairs of degenerate modes in the valleys near the two U points. The latter modes may therefore be assigned a pseudospin. We show that the pseudospin can be switched by scattering the spin wave from decreases of the bias magnetic field, while it is immune to scattering from field increases. Pseudospin creation and read-out can be accomplished using chiral spin-wave transducers, as described in Au et al. [Appl. Phys. Lett. 100, 182404 (2012)] and Au et al. [Appl. Phys. Lett. 100, 172408 (2012)], respectively. Taken together, the possibility of pseudospin creation, manipulation, and read-out suggests a path to development of a spin-wave version of valleytronics ("magnon valleytronics"), in which the pseudospin (rather than amplitude or phase) of spin waves would be used to encode data. Our results are not limited to graded bias magnetic field but can be generalized to other magnonic media with spatially varying characteristics, produced using the toolbox of graded index magnonics.

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Section: Introductionsupporting

confidence: 68%

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

Fripp

Kruglyak

2021

Phys. Rev. B

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“…2 D and E) limited only by the inefficient generation of magnons by the stripline at shorter wavelengths described in detail below. Even with this simple RF waveguide design (SI Appendix) we nevertheless are on par with the optical detection techniques using visible light (29)(30)(31)(32).…”

Section: Detection Of Scattered Wavesmentioning

confidence: 99%

A magnon scattering platform

Zhou

Carmiggelt

Gachter

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Scattering experiments have revolutionized our understanding of nature. Examples include the discovery of the nucleus [R. G. Newton, Scattering Theory of Waves and Particles (1982)], crystallography [U. Pietsch, V. Holý, T. Baumback, High-Resolution X-Ray Scattering (2004)], and the discovery of the double-helix structure of DNA [J. D. Watson, F. H. C. Crick, Nature 171, 737–738]. Scattering techniques differ by the type of particles used, the interaction these particles have with target materials, and the range of wavelengths used. Here, we demonstrate a two-dimensional table-top scattering platform for exploring magnetic properties of materials on mesoscopic length scales. Long-lived, coherent magnonic excitations are generated in a thin film of yttrium iron garnet and scattered off a magnetic target deposited on its surface. The scattered waves are then recorded using a scanning nitrogen vacancy center magnetometer that allows subwavelength imaging and operation under conditions ranging from cryogenic to ambient environment. While most scattering platforms measure only the intensity of the scattered waves, our imaging method allows for spatial determination of both amplitude and phase of the scattered waves, thereby allowing for a systematic reconstruction of the target scattering potential. Our experimental results are consistent with theoretical predictions for such a geometry and reveal several unusual features of the magnetic response of the target, including suppression near the target edges and a gradient in the direction perpendicular to the direction of surface wave propagation. Our results establish magnon scattering experiments as a platform for studying correlated many-body systems.

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“…It is noteworthy that some recent progress in studying spin waves in YIG using TR-STXM has been made via, e.g. transferring a lamella of YIG thin film from a gadolinium gallium garnet (GGG) substrate to a silicon nitride membrane [248] or etching away the underlying GGG substrate [249].…”

Section: Time Resolved Scanning Transmission X-ray Microscopymentioning

confidence: 99%

Magnetic texture based magnonics

Yu,

Xiao,

Schultheiss

2020

Preprint

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The spontaneous magnetic orders arising in ferro-, ferri-and antiferromagnets stem from various magnetic interactions. Depending on the interplay and competition among the Heisenberg exchange interaction, Dzyaloshinskii-Moriya exchange interaction, magnetic dipolar interaction and crystal anisotropies, a great variety of magnetic textures may be stabilized, such as magnetic domain walls, vortices, Skyrmions and spiral helical structures.While each of these spin textures responds to external forces in a specific manner with characteristic resonance frequencies, they also interact with magnons, the fundamental collective excitation of the magnetic order, which can propagate in magnetic materials free of charge transport and therefore with low energy dissipation.Recent theories and experiments found that the interplay between spin waves and magnetic textures is particularly interesting and rich in physics. In this review, we introduce and discuss the theoretical framework of magnons living on a magnetic texture background, as well as recent experimental progress in the manipulation of magnons via magnetic textures. The flexibility and reconfigurability of magnetic textures are discussed regarding the potential for applications in information processing schemes based on magnons.

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Direct observation of coherent magnons with suboptical wavelengths in a single-crystalline ferrimagnetic insulator

Cited by 27 publications

References 49 publications

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

A magnon scattering platform

Magnetic texture based magnonics

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