Magnetoacoustic waves: towards a new paradigm of on-chip communication

Researchers have observed directly and for the first time magnetoacoustic waves (sound-driven spin waves), which are considered as potential information carriers for novel computation schemes. These waves have been generated and observed on hybrid magnetic-piezoelectric devices. The experiments were designed as part of a collaboration between the University of Barcelona (UB), the Institute of Materials Science of Barcelona (ICMAB-CSIC) and ALBA Synchrotron. The results show that magnetoacoustic waves can travel over long distances -up to centimeters- and have larger amplitudes than expected. The observation of the magnetization waves was performed in a Nickel ferromagnetic thin film, which was agitated by a deformation wave (called surface acoustic wave, SAW) originated in a piezoelectric substrate layer below the Nickel film. Although clear interaction between acoustic waves and magnetization dynamics has been reported in several systems, no direct observation of the underlying magnetic agitations existed, providing a quantification of both time and space.

Now, researchers have published their results in Physical Review Letters: “We designed an experiment ad hoc to image and quantify the magnetization dynamics generated by surface acoustic waves (SAW). The results clearly show that magnetization waves exist at distinct frequencies and wavelengths and that it is possible to create wave interferences” explains Ferran Macià, leader of the project at the Institute for Nanoscience and Nanotechnology of the University of Barcelona (IN2UB) and ICMAB.

The experiments show interference patterns of magnetization waves and provide new avenues for manipulation of these waves at room temperature “Our magnetization waves are coupled to the acoustic waves and thus, can travel long distances and have larger amplitudes than spin waves” explains Michael Foerster, beamline scientist of CIRCE-PEEM at ALBA. Such large-amplitude, long-distance waves could be well-suited for carrying information, processing data, or driving small motors.

The generation of magnetization dynamics through acoustic waves has attracted interest because it has some advantages over magnetic field induced excitations, such as more energy efficiency, larger spatial extension, or match of wavelengths.

The experiments were performed using the PEEM (Photoemission Electron Microscopy) at the CIRCE beamline at the ALBA Synchrotron to image the magnetization waves, which were synchronized with the synchrotron light pulses. “As waves are dynamic objects, they were imaged with stroboscopic snapshots thanks to this synchronization. The X-ray magnetic circular dichroism (XMCD) effect was used to obtain magnetic contrast in the images” explains Macià.

The study, in collaboration with the Paul-Drude-Institut in Berlin, was part of a Frontier Interdisciplinary Project (FIP) of the ICMAB Severo Ochoa grant. The FIPs are aimed to develop high-risk exploratory projects of interdisciplinary character to generate cutting-edge research in the application areas of energy, electronics and health.

Article reference:

B. Casals, N. Statuto, M. Foerster, A. Hernández-Mínguez, R. Cichelero, P. Manshausen, A. Mandziak, L. Aballe, J. M. Hernàndez, and F. Macià."Generation and imaging of magnetoacoustic waves over millimeter distances" Physical Review Letters, April 2020. DOI: 10.1103/PhysRevLett.124.137202.

Focus article:

Focus: Sound-Driven Spin Waves April 3, 202. Physics 13, 51.