Abstract
Magnetic domain walls in soft magnetic nanowires often exhibit a structure in which the magnetization curls within the plane of the nanowire around a singular point with out-of-plane magnetization, the vortex core1,2. Although the core is a small object, with a diameter of only ∼10 nm in permalloy2, its motion controls the dynamics of the entire wall, which can be several hundred nanometres in size. In particular, when a domain wall trapped at a pinning site is driven out of equilibrium by either a magnetic field or a spin-polarized current, the vortex core gyrates around its equilibrium position. The sense of gyration is determined by the polarity of the core3,4,5,6,7. Here, we show that spin-polarized a.c. currents can resonantly excite a vortex domain wall trapped at a notched site in a nanowire. The shape and magnitude of the resonance, measured from the nanowire’s resistance, reveal both the elliptical trajectory of the vortex core as well as its polarity.
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Acknowledgements
We thank X. Jiang for helpful discussions and sample fabrication and B. Hughes and K. Roche for technical assistance.
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Moriya, R., Thomas, L., Hayashi, M. et al. Probing vortex-core dynamics using current-induced resonant excitation of a trapped domain wall. Nature Phys 4, 368–372 (2008). https://doi.org/10.1038/nphys936
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DOI: https://doi.org/10.1038/nphys936
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