Fabrication of Nanoparticles and Microspheres with Uniform Magnetic Half-Shells

Abstract

AbstractWe report a method for fabricating, anisotropically designed, multiphasic nano-particles with uniform magnetic half-shells. Cobalt layers were deposited onto commercially made non-magnetic polystyrene nanospheres and microspheres, using ultrahigh vacuum vapor deposition, which produced particles with a half-shell of uniform size, shape and magnetic content. Iron was also deposited onto commercially made silica nanospheres and microspheres and was characterized using transmission electron microscopy and scanning electron microscopy. The coercivity of the magnetic material layers, on the substrate-supported spheres, was enhanced compared to the bulk values of such films without spheres. The particles, once removed from the substrate, were amenable to being rotated in solution, which could allow for more accurate physical and chemical measurements in a variety of fluidic environments. Applications for imaging local mechanical, magnetic and electrical environments are also delineated.