Emission and propagation of 1D and 2D spin waves with nanoscale wavelengths in anisotropic spin textures

Abstract

Spin waves offer intriguing perspectives for computing and signal processing, because their damping can be lower than the ohmic losses in conventional complementary metal–oxide–semiconductor (CMOS) circuits. Magnetic domain walls show considerable potential as magnonic waveguides for on-chip control of the spatial extent and propagation of spin waves. However, low-loss guidance of spin waves with nanoscale wavelengths and around angled tracks remains to be shown. Here, we demonstrate spin wave control using natural anisotropic features of magnetic order in an interlayer exchange-coupled ferromagnetic bilayer. We employ scanning transmission X-ray microscopy to image the generation of spin waves and their propagation across distances exceeding multiples of the wavelength. Spin waves propagate in extended planar geometries as well as along straight or curved one-dimensional domain walls. We observe wavelengths between 1 μm and 150 nm, with excitation frequencies ranging from 250 MHz to 3 GHz. Our results show routes towards the practical implementation of magnonic waveguides in the form of domain walls in future spin wave logic and computational circuits.

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Fig. 1: Spin waves in different geometries.
Fig. 2: Sample layout and magnetic configuration.
Fig. 3: Excitation of spin waves.
Fig. 4: Spin waves in the domain wall.
Fig. 5: Spin wave dispersion relations.
Fig. 6: Domain walls as waveguides.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

The authors thank B. Sarafimov, B. Watts and M. Bechtel for experimental support at the STXM beamlines, as well as C. Fowley, K. Kirsch, B. Scheumann and C. Neisser for their help with sample fabrication. Most of the experiments were performed at the Maxymus endstation at BESSY2, HZB, Berlin, Germany. The authors thank HZB for the allocation of synchrotron radiation beamtime. Some experiments were performed at the PolLux endstation at SLS, PSI, Villigen, Switzerland. Pollux is financed by BMBF via contracts 05KS4WE1/6 and 05KS7WE1. Support by the Nanofabrication Facilities Rossendorf at IBC, HZDR, Dresden, Germany is gratefully acknowledged. V.S. and A.D. acknowledge funding from the Helmholtz Young Investigator Initiative under grant VH-N6-1048. R.A.G. acknowledges financial support from FONDECYT Iniciacion 11170736 and 1161403. A.R.M. acknowledges funding from FONDECYT 3170647; funding from the Basal Program for Centers of Excellence, grant FB0807 CEDENNA, CONICYT is also acknowledged. V.T. and A.S. acknowledge support from the US National Science Foundation under grants EFMA-1641989 and ECCS-1708982 and from the DARPA M3IC grant under contract no. W911-17-C-0031. S.W. acknowledges funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 290605 (PSI-FELLOW/COFUND).

Author information

Affiliations

Authors

Contributions

S.W. conceived the experiment. V.S., M.W. and S.W. performed the STXM measurements. V.S. and S.W. analysed the data. T.S., T.W., A.K. and S.W. conducted the micromagnetic simulations. R.A.G., A.R.M. and P.L. calculated the spin wave dispersion relation. R.M. and S.W. supervised sample preparation. V.S. and S.W. wrote the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Volker Sluka or Sebastian Wintz.

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Competing interests

The authors declare no competing interests.

Additional information

Journal peer review information Nature Nanotechnology thanks Ferran Macià, Takuya Satoh and other anonymous reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

41565_2019_383_MOESM2_ESM.avi

Plane and circular waves excited at 1.11 GHz, with left and right panels showing absolute and normalized contrast, respectively.

41565_2019_383_MOESM3_ESM.avi

Plane and circular waves excited at 1.46 GHz, with left and right panels showing absolute and normalized contrast, respectively.

41565_2019_383_MOESM4_ESM.avi

Plane and circular wave interference at the centre region for the different layers NiFe (top), CoFeB (middle) and the cumulative signal of Fe (bottom), with left and right panels showing absolute and normalized contrast, respectively.

41565_2019_383_MOESM5_ESM.avi

Spin-waves in domain walls with absolute (left) and normalized (right) contrast at 500 MHz (top) and 250 MHz (bottom).

41565_2019_383_MOESM6_ESM.avi

Spin-waves in domain walls excited by a pulse, with absolute (left) and normalized (right) contrast.

41565_2019_383_MOESM7_ESM.avi

Spin wave packet traveling along a curved domain wall (normalized contrast).

41565_2019_383_MOESM8_ESM.avi

Micromagnetic simulation of spin waves in a domain wall (normalized contrast).

Supplementary Information

Supplementary Figures 1–3

Supplementary Movie 1

Plane and circular waves excited at 1.11 GHz, with left and right panels showing absolute and normalized contrast, respectively.

Supplementary Movie 2

Plane and circular waves excited at 1.46 GHz, with left and right panels showing absolute and normalized contrast, respectively.

Supplementary Movie 3

Plane and circular wave interference at the centre region for the different layers NiFe (top), CoFeB (middle) and the cumulative signal of Fe (bottom), with left and right panels showing absolute and normalized contrast, respectively.

Supplementary Movie 4

Spin-waves in domain walls with absolute (left) and normalized (right) contrast at 500 MHz (top) and 250 MHz (bottom).

Supplementary Movie 5

Spin-waves in domain walls excited by a pulse, with absolute (left) and normalized (right) contrast.

Supplementary Movie 6

Spin wave packet traveling along a curved domain wall (normalized contrast).

Supplementary Movie 7

Micromagnetic simulation of spin waves in a domain wall (normalized contrast).

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Sluka, V., Schneider, T., Gallardo, R.A. et al. Emission and propagation of 1D and 2D spin waves with nanoscale wavelengths in anisotropic spin textures. Nat. Nanotechnol. 14, 328–333 (2019). https://doi.org/10.1038/s41565-019-0383-4

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