Author: ["Rai Moriya","Luc Thomas","Masamitsu Hayashi","Yaroslaw B. Bazaliy","Charles Rettner","Stuart S. P. Parkin"]
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Abstract
A magnetic vortex trapped by a notch in a nanowire is no larger than 10 nm, but both the direction and polarity of the vortex can now be measured without applying a magnetic field. In this set-up, the vortex is therefore both stable and switchable for use in possible device applications. 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.Cite this article
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 