Rare-earth-based
core–shell spring nanomagnets have been intensively studied
in the permanent magnet industry. However, the inherent agglomeration
characteristics of zero-dimensional (0-D) magnetic nanoparticles are
an issue in practical fabrication of magnetic nanocomposites due to
deterioration in exchange-coupling interactions, resulting in inferior
magnetic performance. Here, with an aim to overcome the structural
limitations, we report a new type of SmCo/FeCo core–shell nanomagnet
with a well-dispersed one-dimensional (1-D) structure prepared by
a combination of electrospinning and electroless plating processes.
An FeCo layer with a tailored thickness on nanoscale SmCo was produced
to achieve a sufficient exchange-coupling effect. The influence of
electroless plating time on the microstructure of fibers was discussed,
and comparisons were made as a function of the magnet shape. A 1-D
SmCo/FeCo spring nanomagnet having a core diameter ranging from 150
to 200 nm and a shell thickness of 15–20 nm showed a potent
exchange-coupling effect compared with its 0-D counterpart. This effectively
reduced self-aggregation and further showed a remarkable enhancement
in (BH)max (above 45.7%). We think that
this novel structure marks a new era in the exchange-spring magnet
industry and may overcome the limitations of traditional core–shell
nanomagnets.