Abstract
The synchronization of multiple nanocontact spin-torque oscillators (NC-STOs) is mediated by propagating spin waves (SWs). Although it has been shown that the Oersted field generated in the vicinity of the NC can dramatically alter the emission pattern of SWs, its role in the synchronization behaviour of multiple NCs has not been considered so far. Here we investigate the synchronization behaviour in multiple NC-STOs oriented either vertically or horizontally, with respect to the in-plane component of the external field. Synchronization is promoted (impeded) by the Oersted field landscape when the NCs are oriented vertically (horizontally) due to the highly anisotropic SW propagation. Not only is robust synchronization between two oscillators observed for separations larger than 1,000 nm, but synchronization of up to five oscillators, a new record, has been observed in the vertical array geometry. Furthermore, the synchronization can no longer be considered mutual in nature.
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Acknowledgements
This work was supported by the European Commission FP7-ICT-2011 contract No. 317950 “MOSAIC”. It was also supported by the European Research Council (ERC) under the European Community's Seventh Framework Programme (FP/2007-2013)/ERC Grant 307144 “MUSTANG”. Support from the Swedish Research Council (VR), the Swedish Foundation for Strategic Research (SSF), and the Knut and Alice Wallenberg Foundation is gratefully acknowledged.
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A.H. and P.D. fabricated the devices and A.H. performed all the electrical measurements. A.H. and E.I. performed the micromagnetic simulations. R.K.D. and J.Å. initiated and supervised the project. All authors contributed to the data analysis and co-wrote the manuscript.
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Houshang, A., Iacocca, E., Dürrenfeld, P. et al. Spin-wave-beam driven synchronization of nanocontact spin-torque oscillators. Nature Nanotech 11, 280–286 (2016). https://doi.org/10.1038/nnano.2015.280
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DOI: https://doi.org/10.1038/nnano.2015.280
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