Three-Dimensional Self-Assembly of Metallic Rods with Submicron Diameters Using Magnetic Interactions

Abstract

This paper describes the three-dimensional (3D) self-assembly of metallic rods with submicron diameters into highly stable microstructures using magnetic interactions to guide the assembly process. The rods contained alternating sections of ferromagnetic and diamagnetic materials. The ferromagnetic sections were disks, that is, their thickness (t) was less than their diameter (d), and their dominant (or “easy”) axis of magnetization was perpendicular to the long axis of the rods. After these rods were magnetized, they spontaneously assembled into stable “bundles ” in the absence of an external field. This work demonstrates that the magnetic profile of individual components can direct and stabilize the formation of ordered, 3D structures by self-assembly. The application of a magnetic field to a suspension of magnetic particles (microspheres, nanoparticles, and rods) typically produces one-dimensional (1D) chains of particles with their magnetic dipole