Exchange coupled nanoparticles

composite Image of top: journal cover showing excellent alignment achievable in coupled particles.  Bottom – Left: TEM-EDS of the core-shell particles. Right: M(H) loop at 80 K, with bulk values as solid line, and element-specific XMCD measurements for core (Ni) and shell (Co) shown as dots.

CMI researchers from Ames National Laboratory and Lawrence Livermore National Laboratory conducted the research for this highlight.

Unambiguous demonstration of magnetic exchange coupling in metal-oxide core-shell nanoparticles.

Demonstration of 3d exchange coupling between Ni nanoparticles and their CoFe2O4 shell. The Ni core has zero coercivity by itself but when coated develops a large coercivity that matches the magnetically hard CoFe2O4 shell.

Significance and Impact
Interface quality and production scaling have, to now, stymied the deployment of exchange-coupled magnets. This result is the first clear demonstration of the process in air-stable materials with an approach scalable to bulk production.

Hub Goal Addressed
Reduce chemical, material, and energy intensity of mineral and materials processing.