Three Dimensional Self Assembly of Core/Shell Like Nanostructures for High Performance Nanocomposite Permanent Magnets.
Core/shell nanostructures are fascinating for many advanced applications including strong permanent magnets, magnetic recording, and biotechnology. They are generally achieved via chemical approaches, but these techniques limit them to nanoparticles. Here, we describe a three dimensional (3D) self assembly of core/shell like nanocomposite magnets, with hard magnetic Nd2Fe14B core of ~45 nm and soft magnetic a Fe shell of ~13 nm, through a physical route. The resulting Nd2Fe14B/a Fe core/shell like nanostructure allows both large remanent magnetization and high coercivity, leading to a record high energy product of 25 MGOe which reaches the theoretical limit for isotropic Nd2Fe14B/a Fe nanocomposite magnets. Our approach is based on a sequential growth of the core and shell nanocrystals in an alloy melt. These results make an important step toward fabricating core/shell like nanostructure in 3D materials.
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