The ongoing exponential increase in data traffic threatens with saturating the narrow spectrum of today’s networks. To overcome this issue, the fifth generation of wireless technology (5G) is shifting to higher frequencies, into the mm-waves, where plenty of bandwidth is available. A big challenge of mm-waves is that these only allow line-of sight propagation, making the transition to higher frequencies a real paradigm change, with the communications relying on myriads of closely scattered small antennas. Thus, besides working at tens to hundreds of GHz, the new communication devices will have to be cheap, low power and miniaturized. This will in particular affect the ferrite non-reciprocal devices, such as the circulators which isolate emitting antennas from one another. The ferrites currently used in non-reciprocal wireless components only operate in the first portion of the mm-wave band, using external magnetic fields which makes them bulky, expensive and can only work at one frequency. The key functional property of ferrites in those devices is their ferromagnetic resonance (FMR) by which, at a given frequency, the propagation or absorption of electromagnetic waves through a ferrite depends on their direction with respect to the magnetization. Since the frequency at which the FMR occurs increases with the magnetic anisotropy of the ferrite, very high magnetic anisotropy ferrites are needed for operating at mm-waves.
The overall objective of FeMiT is developing a new family of ferrites based on epsilon-Fe2O3, a material with a high magnetic anisotropy, which can work in non-reciprocal wireless components at higher frequencies without the need of external magnetic fields.