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arXiv · 2103.10156

Cherenkov radiation of spin waves by ultra-fast moving magnetic flux quanta

O. V. Dobrovolskiy·Q. Wang·D. Yu. Vodolazov·B. Budinska·S. Knauer·R. Sachser·M. Huth·A. I. Buzdin
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Abstract

Despite theoretical predictions for a Cherenkov-type radiation of spin waves (magnons) by various propagating magnetic perturbations, fast-enough moving magnetic field stimuli have not been available so far. Here, we experimentally realize the Cherenkov radiation of spin waves in a Co-Fe magnonic conduit by fast-moving (>1 km/s) magnetic flux quanta (Abrikosov vortices) in an adjacent Nb-C superconducting strip. The radiation is evidenced by the microwave detection of spin waves propagating a distance of 2 micrometers from the superconductor and it is accompanied by a magnon Shapiro step in its current-voltage curve. The spin-wave excitation is unidirectional and monochromatic, with sub-40 nm wavelengths determined by the period of the vortex lattice. The phase-locking of the vortex lattice with the excited spin wave limits the vortex velocity and reduces the dissipation in the superconductor.

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O. V. Dobrovolskiy, Q. Wang, D. Yu. Vodolazov, B. Budinska, S. Knauer, R. Sachser, M. Huth, A. I. Buzdin. 2023-02-13. Cherenkov radiation of spin waves by ultra-fast moving magnetic flux quanta. https://arxiv.org/abs/2103.10156

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