Monomolecular cross-linked highly dense cubic FeCo nanocomposite for high-frequency application

Well-dispersed silica-coated FeCo nanocubes are mass prepared using the polyol process and are then amine-functionalized with 1,6- diaminohexane. Further, the almost “matrix-free” soft magnetic nanocomposites (SMNCs) are fabricated using the FeCo nanocubes as bricks, which are cross-linked by epoxy monomers in which the nanoparticles are well separated. These SMNCs exhibit a dense microstructure and extremely high resistivity that limit the eddy current loss, thereby allowing excellent high-frequency inductance performance in a few hundred megahertz and extending the cutoff frequency to 2–7 GHz. The permeability is approximately 8.0 with excellent high-frequency stability at 1 GHz. The quality factor of the nanocomposites exceeds 200 in the 100 MHz range and 500 in the few megahertz range that corresponds to the 36 and 13 nm silica-coating samples, respectively. Furthermore, they exhibit a novel microwave absorbing property with an extremely thin thickness. The absorption approaches − 46.5 dB at 2.41 GHz with only a 1.75 mm nanocomposite absorbing layer. This SMNC presents great potential as multifunction components to satisfy the urgent requirement of wide bandgap semiconductor power in the megahertz range and microwave devices in the gigahertz range. Graphical abstract