FEBID-grown iron and cobalt nanowires as magnetic force sensors

Nanowires (NW) fabricated by focused electron beam induced deposition (FEBID) of magnetic materials such as iron and cobalt [1] are ideal candidates as magnetic force transducers [2]. The ability to produce nanometer-scale structures with extremely high aspect ratios should allow for magnetic probes with both high force sensitivity and fine spatial resolution. Here, we characterize the mechanical properties of magnetic FEBID-grown NWs using optical interferometry. Furthermore, we study their magnetic behavior through measurements of dynamic torque magnetometry [2]. Due to the large shape anisotropy, the equilibrium magnetization points along the NW, giving rise to a tiny magnetic monopole-like tip for magnetic force sensing. We confirm such behavior by scanning the NW over a micron-sized, current-carrying wire and recording its mechanical response driven by the Biot-Savart magnetic field. Our results, combined with ongoing progress in FEBID manufacturing of nanowires, hold great promise for new types of mechanical sensors for magnetic field imaging at the nanometer-scale.

[1] J. Pablo-Navarro et al., J. Phys. D: Appl. Phys. 50, 18LT01 (2017)
[2] N. Rossi et al., arXiv:1810.10865