Magnetic force driven orientation of Co23B10 arrays inspired by magnetotactic bacteria

Ordered submicron ferromagnetic Co-B arrays were obtained through a biomimetic process at ambient temperature. When Co2+ ions complexed to soluble starch were reduced by potassium borohydride in a magnetic field, the magnetic force allowed the nanoparticles of Co-B alloys to array along the field lines and deposit on a solid support. This process is inspired by the migration mechanism of magnetotactic bacteria in a geomagnetic field and this convenient strategy should be helpful for the production of ordered arrays of other magnetic materials. After Co-B alloys are assembled into ordered chains, they exhibit strong ferromagnetic signals in the variable temperature ferromagnetic resonance spectra in the temperature range of 100-420 K.