Reconfigurable Spin-Wave Nonreciprocity Induced by Dipolar Interaction in a Coupled Ferromagnetic Bilayer

Gallardo, R. A.; Schneider, Tobias; Chaurasiya, Avinash Kumar; Oelschlägel, A.; Arekapudi, Sri Sai Phani Kanth; Roldán-Molina, A.; Hübner, René; Lenz, K.; Barman, Anjan; Faßbender, J.; Lindner, J.; Hellwig, Olav; Landeros, P.

doi:10.1103/physrevapplied.12.034012

Cited by 107 publications

(88 citation statements)

References 80 publications

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“…Such a change of sign has also been predicted for films where breaking of the top-bottom magnetic symmetry is not obtained through a blockwise variation of M S , like here, but rather by a grading of saturation magnetization across the thickness [22]. In contrast, it has not been observed for bilayers where the two magnetic materials, being separated by a nonmagnetic spacer, are coupled only through longrange dipole interactions [41,42]. This further demonstrates the essential role played by short-range out-of-plane exchange coupling in this phenomenon.…”

Section: B Nonreciprocal Dispersion Relationssupporting

confidence: 70%

Slow-Wave-Based Nanomagnonic Diode

et al. 2020

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Spin waves, the collective excitations of the magnetic order parameter, and magnons, the associated quasiparticles, are envisioned as possible data carriers in future wave-based computing architectures. On the road toward spin-wave computing, the development of a diodelike device capable of transmitting spin waves in only one direction, thus allowing controlled signal routing, is an essential step. Here we report on the design and experimental realization of a microstructured magnonic diode in a ferromagnetic bilayer system. Effective unidirectional propagation of spin waves is achieved by taking advantage of nonreciprocities produced by dynamic dipolar interactions in transversally magnetized media, which lack symmetry about their horizontal midplane. More specifically, dipolar-induced nonreciprocities are used to engineer the spin-wave dispersion relation of the bilayer system so that the group velocity is reduced to very low values for one direction of propagation and not for the other, thus producing unidirectional slow spin waves. Brillouin light scattering and propagating-spin-wave spectroscopy are used to demonstrate the diodelike behavior of the device, the composition of which is first optimized through micromagnetic simulations.

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Section: B Nonreciprocal Dispersion Relationssupporting

confidence: 70%

Slow-Wave-Based Nanomagnonic Diode

et al. 2020

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“…However, it proves to be highly challenging to fabricate low-damping YIG on conventional substrates, such as Si [65] and GaAs [66]. The nonreciprocity effect induced by the dipolar interaction between top and bottom layers should be negligible since the parallel magnetic configuration can be established with a small field [37,67] To summarize, we have observed chiral spin-wave velocities in ultrathin YIG films induced by DMI attributed to the YIG/GGG interface. The drift group velocity is about 40 m/s yielding a DMI constant of 16 µJ/m 2 .…”

mentioning

confidence: 99%

Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

et al. 2020

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Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI) which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7 nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e. the film normal direction, applied field and spin-wave wavevector. By measuring the asymmetric group velocities, we extract a DMI constant of 16 µJ/m 2 which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultra-low spin-wave damping can be achieved. arXiv:1910.02599v2 [cond-mat.mtrl-sci]

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“…Nonreciprocal frequency shift for thermally excited "incoherent" spin waves due to asymmetric spin wave dispersion have been experimentally observed by Brillouin light scattering techniques (22)(23)(24)(25)(26)(27). In the past few years, spin wave nonreciprocity in SAFs was micromagnetically calculated and experimentally observed (28)(29)(30)(31). However, despite the recent extensive studies on the research field of magnonics and antiferromagnetic spintronics, there have been few studies on antenna-excited "coherent" propagating spin waves in SAFs.…”

Section: Introductionmentioning

confidence: 99%

Switchable giant nonreciprocal frequency shift of propagating spin waves in synthetic antiferromagnets

Ishibashi

Shiota

et al. 2020

Sci. Adv.

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The nonreciprocity of propagating spin waves, i.e., the difference in amplitude and/or frequency depending on the propagation direction, is essential for the realization of spin wave–based logic circuits. However, the nonreciprocal frequency shifts demonstrated so far are not large enough for applications because they originate from interfacial effects. In addition, switching of the spin wave nonreciprocity in the electrical way remains a challenging issue. Here, we show a switchable giant nonreciprocal frequency shift of propagating spin waves in interlayer exchange–coupled synthetic antiferromagnets. The observed frequency shift is attributed to large asymmetric spin wave dispersion caused by a mutual dipolar interaction between two magnetic layers. Furthermore, we find that the sign of the frequency shift depends on relative configuration of two magnetizations, based on which we demonstrate an electrical switching of the nonreciprocity. Our findings provide a route for switchable and highly nonreciprocal spin wave–based applications.

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Reconfigurable Spin-Wave Nonreciprocity Induced by Dipolar Interaction in a Coupled Ferromagnetic Bilayer

Cited by 107 publications

References 80 publications

Slow-Wave-Based Nanomagnonic Diode

Slow-Wave-Based Nanomagnonic Diode

Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

Switchable giant nonreciprocal frequency shift of propagating spin waves in synthetic antiferromagnets

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