Fast fabrication of a hierarchical nanostructured multifunctional ferromagnet.

Materials with multifunctionality affect society enormously. However, the inability to surmount multiple functionality trade-offs limits the discovery of next-generation multifunctional materials. Departing from conventional alloying design philosophy, we present a hierarchical nanostructure (HNS) strategy to simultaneously break multiple performance trade-offs in a material. Using a praseodymium-cobalt (PrCo 5 ) ferromagnet as a proof of concept, the resulting HNS outperforms contemporary high-temperature ferromagnets with a 50 to 138% increase in electrical resistivity while achieving their highest energy density. Our strategy also enables an exceptional thermal stability of coercivity (-0.148%/°C)-a key characteristic for device accuracy and reliability-surpassing that of existing commercial rare-earth magnets. The multifunctionality stems from the deliberately introduced nanohierarchical structure, which activates multiple micromechanisms to resist domain wall movement and electron transport, offering an advanced design concept for multifunctional materials.