Spin waves and magnetoresistive sensors: a nanometric encounter
Physicists from several laboratories in France, within the framework of the SPIN Research Program for the targeted SWING project, have detected spin waves at the nanometer scale by coupling them to a magnetoresistive sensor operating at very high frequency. Their paper ‘Magneto-resistive detection of spin-waves’ was published in Science Advances on August 15, 2025
Spin waves, which physicists also call magnons, are essentially tiny vibrations within magnetic materials. Recently, researchers have been envisioning them as the basis for a new kind of information-processing circuits, called magnonics. The idea? To take advantage of both the ease with which these waves propagate and the natural ability of magnets to store information. For this to become possible, it is necessary to link these waves to the world of electronics—that is, to convert them into usable electrical signals, and to do so at the nanometer scale, the one used in today’s technologies. Until now, the available techniques—such as certain optical or inductive methods—have struggled to detect these waves at sub-micrometer scales
Researchers from several laboratories in France, including the Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS, CNRS/Université de Strasbourg) and the Service de Physique de l’État Condensé (SPEC, CEA Saclay/CNRS), have developed a novel method to efficiently detect spin waves. Their approach consists in placing a giant magnetoresistance (GMR) sensor directly beneath a spin-wave waveguide. As the waves propagate nearby, they slightly modify the magnetization of one of the sensor’s layers, which in turn causes a change in its electrical resistance. This variation is then converted into a measurable signal at frequencies on the order of a few gigahertz. A key result: the device delivers a signal about fifty times stronger than that obtained with the conventional inductive method, for a comparable detection area. This demonstrates the effectiveness of GMR for probing spin waves at very high frequencies and at the nanometer scale
These experimental observations were confirmed by numerical simulations, which accurately reproduce the results. And the team is already looking ahead: by using even more sensitive sensors, such as those based on tunnel magnetoresistance (TMR), the signal could be further amplified. In the long term, this breakthrough paves the way for ultra-compact spin-wave sensors capable of operating in extreme regimes — below 100 nanometers or even with waves generated by thermal fluctuations. It also brings magnonics closer to integration into conventional electronic circuits, opening the door to new architectures that are faster and more energy-efficient
Co-autors: Quentin Rossi*, Grégoire De Loubens, Hugo Merbouche, Aurélie Solignac, Matthieu Bailleul*, Daniel Stoeffler, Igor Ngouania, Yves Henry, Hicham Majjad
