Nanostructured magnets prepared by magnetophoresis-assisted capillary assembly of Co nanorods

Abstract

The fabrication of micrometric magnetic materials and their integration into portable devices reveal great interests for telecommunications, automotive, biomedical and space applications, but still remain highly challenging.The bottom-up approach for nanostructured magnets is an interesting alternative route to the classical rare earth metallurgy or thin film deposition. Indeed, the recent progresses in the magnetic nanoparticle synthesis allow a good control of the particle size, shape and chemical composition. Single-crystalline Co nanorods (NRs), which combine a high magnetization and a large magnetic anisotropy, can be prepared by the polyol process [1]. These anisotropic particles constitute building blocks of primary choice for permanent magnet applications. [2]We reported recently a versatile approach for the fabrication and direct integration of nanostructured magnetic materials of controlled shaped at specific locations onto silicon substrates [3]. The magnetophoresis-assisted capillary assembly of magnetic nanoparticles leads to the fabrication of high-performance Co-based permanent magnets (Figure 1).Integrated submillimeter magnets as well as millimetric self-standing magnets exhibiting magnetic properties competing with NdFeB-based composited were obtained through this cost- and time-efficient process. The proof-of-concept of electromagnetic actuation of a MEMS cantilever by means of these supercrystals highlights their potentiality as efficient integrated magnetic materials within nomadic devices.  Nanostructured magnets prepared by magnetophoresis-assisted capillary assembly of Co nanorods