Abstract
The interplay between spin, charge and orbital degrees of freedom has led to the development of spintronic devices such as spin–torque oscillators and spin-transfer torque magnetic random-access memories. In this development, spin pumping represents a convenient way to electrically detect magnetization dynamics1,2,3,4,5,6. The effect originates from direct conversion of low-energy quantized spin waves in the magnet, known as magnons, into a flow of spins from the precessing magnet to adjacent leads. In this case, a secondary spin–charge conversion element, such as heavy metals with large spin Hall angle4,5,6 or multilayer layouts7, is required to convert the spin current into a charge signal. Here, we report the experimental observation of charge pumping in which a precessing ferromagnet pumps a charge current, demonstrating direct conversion of magnons into high-frequency currents via the relativistic spin–orbit interaction. The generated electric current, unlike spin currents generated by spin-pumping, can be directly detected without the need of any additional spin–charge conversion mechanism. The charge-pumping phenomenon is generic and gives a deeper understanding of its reciprocal effect, the spin orbit torque, which is currently attracting interest for their potential in manipulating magnetic information.
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Acknowledgements
A.F. acknowledges support from a Hitachi Research Fellowship and C.C. from a Junior Research Fellowship at Gonville and Caius College. V.N. acknowledges MSMT grant no. LM2011026.
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K.H. and A.B. developed the theory and suggested the experiment. C.C. and A.J.F. developed the experimental technique and performed the experimental work. V.N. grew the materials. A.I. performed the nanofabrication. C.C., K.H., A.B. and A.F. wrote the manuscript. All authors discussed the results and commented on the paper.
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Ciccarelli, C., Hals, K., Irvine, A. et al. Magnonic charge pumping via spin–orbit coupling. Nature Nanotech 10, 50–54 (2015). https://doi.org/10.1038/nnano.2014.252
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DOI: https://doi.org/10.1038/nnano.2014.252
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