Magnetic force driven orientation of Co23B10 arrays inspired by magnetotactic bacteria

Abstract

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.