Future spintronic devices will require fast, strong, localized magnetic fields (or effective magnetic fields) in an integrated platform. Ferromagnetic (FM) vortices provide a route towards this requirement. Here, we show that a FM vortex meets these criteria when coupled to nitrogen-vacancy (NV) center spins in diamond. NVs are an increasingly attractive candidate for applications in both spin-based sensing and quantum information processing due to their long coherence times at room temperature, and nanoscale size. But to take advantage of the NV's small size, individual spins must be addressable on nanometer length scales, for individual manipulation and read-out of the spin state, and to control coupling between proximal spins. First, we show that an integrated FM vortex can provide a local magnetic field exceeding 10 mT. Second, we find that the magnetic field gradient produced by the vortex is sufficient to address spins separated by nanometer length scales. By applying a microwave-frequency magnetic field, we drive both the vortex and the NV spins, resulting in enhanced coherent rotation of the spin state. Finally we demonstrate that the vortex position can be controlled on a 100 ns timescale, allowing for sequential addressing and coherent manipulation of spins.
Wolf, M. S., Badea, R., & Berezovsky, J. (2016). Fast nanoscale addressability of nitrogen-vacancy spins via coupling to a dynamic ferromagnetic vortex. Nature Communications, 7. https://doi.org/10.1038/ncomms11584