This paper discusses on the miniaturization of radiofrequency (RF) front-end components such as half-wavelength resonators based on new magneto-dielectric heterostructures combining high permeability (µ = 150–250) and high permittivity (ε = 18–150). Size reduction is evaluated by means of 2-cm-long coplanar waveguides realized with silicon technology and having a resonance frequency of about 3 GHz. The experimental results show a physical length reduction of 11.2% due to the dielectric contribution (ε = 18) and 14.8% by cumulating dielectric and magnetic effects (ε = 18 and µ = 150). These results are significant with respect to the moderate thickness of the preliminary material used here (only 150 nm). In a second part, a predictive model is proposed with µ and ε as variables. When adjusting the material properties in a realistic way (µ = 250 and ε = 150), the model predicts size reduction of ~50% for the same thickness. Larger values can be expected with increasing the film thickness.

The production of remanence enhanced powders, using a method of mechanical alloying of free iron to melt spun ribbon, has been studied. The final composition is Nd8. 1Fe77.1Co10.9B3.9 and both hard and soft materials possess an initial fine grain size; approximately 30nm for the Nd2Fe14B phase in the melt spun ribbon and 1µm for the α-Fe. The magnetic properties of resin bonded magnets fabricated using such material have been measured and found to exhibit exchangespring behaviour. The experiments performed in this work are described with respect to the volume fraction of the soft phase and subsequent annealing temperature of the as-milled material. Remanence enhancement has been observed and this can be attributed to the exchange interactions between the ferromagnetic soft and hard phases. For a 30% by volume addition of α-Fe, typical values of remanence were found to be ∼880mT with a coercivity of ∼250 kA/m. The reversible and irreversible components of the magnetisation have been determined, to demonstrate the exchange coupling and coercivity behaviours respectively.