Wireless communication technologies such as smartphones use local oscillators to generate or detect signals. However, the size of the components of these oscillators (capacitors and inductors) limits the speed with which frequencies can be controlled. The continual increase in information throughput demands, especially for connected objects, is prompting interest in "spin-torque nano-oscillators" (STNOs). These new oscillators consist of thin-layered "stacks" that are significantly smaller (100 nm) and offer greater flexibility in controlling the frequency of signals.

In their work, the researchers implemented a spectrum analyzer using a spin-torque nano-oscillator. The principle is to "mix" the signal to be detected with that of a variable frequency oscillator. The frequency sweep of the STNO could be performed in less than a hundred nanoseconds (instead of more than one microsecond with a conventional oscillator) – an unprecedented achievement! Moreover, this spectrum analyzer made it possible to resolve several frequency components simultaneously as well as to track rapid changes in frequency.

This work was carried out as part of an ERC Magical grant in collaboration with Oakland University (USA) and the International Iberian Nanotechnology Laboratory in Braga (Portugal).