Mechanical magnetometry of Cobalt nanospheres deposited by focused electron beam at the tip of ultra-soft cantilevers

Abstract Using focused-electron-beam-induced deposition, Cobalt magnetic nanospheres with diameter ranging between 100 nm and 300 nm are grown at the tip of ultra-soft cantilevers. By monitoring the mechanical resonance frequency of the cantilever as a function of the applied magnetic field, the hysteresis curve of these individual nanospheres are measured. This enables the evaluation of their saturation magnetization, found to be around 430 emu/cm3 independent of the size of the particle, and to infer that the magnetic vortex state is the equilibrium configuration of these nanospheres at remanence. SEM image of a 200 nm Co nanosphere grown at the tip of an ultra-soft cantilever by focus electron beam induced deposition.