Inkjet printing of hard magnetic iron‑platinum thin films

FePt alloys are known for their exceptional hard magnetic properties, which translate into high coercivity, saturation magnetization and energy product. Their capability to efficiently retain permanent magnetization makes them attractive for applications like data storage, sensors, energy harvesters, microactuators and biomedical microrobotics. The present study investigates the deposition of hard magnetic FePt thin layers via inkjet printing (IJP), providing the first demonstration of FePt thin films deposition using this versatile and scalable technique. FePt nanoparticles (NPs) are synthesized using a facile water-based reduction method and subsequently dispersed in a green organic solvent to formulate printable inks. The inkjet printing process is optimized to achieve uniform layers with controlled thickness, which are annealed in a reducing atmosphere at various temperatures to induce the formation of the chemically ordered L10 phase. A comprehensive morphological, structural, and magnetic characterization confirms the formation of uniform and adherent layers with significant coercivity and magnetization, particularly after annealing at 750 ◦C. Under these conditions, a coercivity up to 794 mT and a remanence up to 36 A m2 kg− 1 can be obtained. The results obtained indicate that inkjet printing is a viable and scalable technique for producing high-performance FePt magnetic layers, with potential applications in many industrial sectors.