Magnetic force sensing using a self-assembled GaAs nanowire with a MnAs tip

We present a scanning magnetic force sensor based on an individual magnet-tipped GaAs nanowire (NW) grown by molecular beam epitaxy [1]. Its magnetic tip consists of a final segment of single-crystal MnAs formed by sequential crystallization of the liquid Ga catalyst droplet [2]. We characterize the mechanical and magnetic properties of such NWs by measuring their flexural mechanical response in an applied magnetic field [3]. Comparison with numerical simulations allows the identification of their equilibrium magnetization configurations, which in some cases include magnetic vortices. We determine a NW's performance as a scanning probe [4], by measuring its dynamical response to the magnetic field of a micrometric current-carrying wire. The NWs' tiny tips and their high force sensitivity make them promising for imaging weak magnetic field patterns on the nanometer-scale, as required for mapping mesoscopic transport and spin textures or in nanometer-scale magnetic resonance.

[1] N. Rossi et al., arXiv:1810.10865
[2] J. Hubmann et al., Nano Lett. 16, 900 (2016)
[3] B. Gross et al., Phys. Rev. B 93, 064409 (2016)
[4] N. Rossi et al. Nat. Nanotech. 12, 150 (2017)