Georgetown researchers created rare‑earth‑free, high‑anisotropy magnets using C16 high‑entropy borides and combinatorial synthesis, matching near‑record performance.
Researchers at Georgetown University report a new class of strong, rare‑earth‑free magnets based on high‑entropy borides that use earth‑abundant 3d transition metals and boron.
By stabilizing a tetragonal C16 crystal structure — a lower‑symmetry phase favorable for uniaxial anisotropy — the team engineered materials whose magnetization strongly prefers a single direction. They synthesized quinary boride compositions with combinatorial co‑sputtering, allowing rapid exploration of dozens of compositions on a single heated substrate.
Key experimental findings include a significant increase in magnetic anisotropy and coercivity compared with binary and ternary transition‑metal borides, with performance approaching that of some rare‑earth permanent magnets. Density functional theory calculations reproduce the trends and point to optimized electronic structure (valence electron concentration and effective magnetic moment) as the origin of the enhanced anisotropy.
The approach provides a boron‑assisted route to ordered high‑entropy magnetic materials without precious or rare‑earth elements. Potential applications range from heat‑assisted magnetic recording and spintronic devices to energy‑efficient permanent magnets for motors, robotics, and medical imaging. The team is continuing composition searches, aided by machine learning, and has a pending patent on boron‑based high‑entropy magnetic materials.