New technique to see surface acoustic waves and their effects on nanomagnetic materials
Joan Manel Hernàndez, Sergi Lendínez and Nahuel Statuto, from the Department of Condensed Matter Physics of the University of Barcelona, have taken part in the development of a new experimental technique that enables researchers to use surface acoustic waves to improvement data storage and processing. UB researchers have worked together with other researchers from ALBA Synchrotron and the Institute for Materials Science of Barcelona (IMCAC-CSIC) in collaboration with the Paul Scherrer Institut (Switzerland), the Johannes Gutenberg University Mainz and the Paul Drude Institut (both in Germany).
One of the methods under research to alter the magnetic properties of materials and to improve the data storage and processing is based on the elastic deformation of magnetic material to modify its magnetic properties.
Joan Manel Hernàndez, Sergi Lendínez and Nahuel Statuto, from the Department of Condensed Matter Physics of the University of Barcelona, have taken part in the development of a new experimental technique that enables researchers to use surface acoustic waves to improvement data storage and processing. UB researchers have worked together with other researchers from ALBA Synchrotron and the Institute for Materials Science of Barcelona (IMCAC-CSIC) in collaboration with the Paul Scherrer Institut (Switzerland), the Johannes Gutenberg University Mainz and the Paul Drude Institut (both in Germany).
One of the methods under research to alter the magnetic properties of materials and to improve the data storage and processing is based on the elastic deformation of magnetic material to modify its magnetic properties.
One way to create fast deformation changes, up to a subnanosecond scale and thus, induce magnetization changes, is to use surface acoustic waves (SAW), which are deformation waves. Thesewaves work similar to a wave of deformation in an iron bar when it is hammered in one side. A surface acoustic wave spreads deformation but only in the surface, like ocean waves. In the piezoelectric materials, those that expand or contract when applying voltage, these waves can be generated out of oscillating electric fields.
The mentioned researchers have worked on a new experimental technique to quantitatively visualize these surface acoustic waves and use them to alter the magnetization of magnetic nanoelements on the surface layer of a crystal.
Magnetic properties, frame by frame
The experiment was carried out in the CIRCE beamline of ALBA Synchrotron, during the PhotoEmission Electron Microscope (PEEM), a cutting-edge tool to analyze thin layers, surfaces and interfaces as well as magnetic properties in nanomaterials.
Researchers prepared these magnetic squares put on a piezoelectric crystal. Using ALBAʼs Synchrotron acceleratorsʼ time signal as a reference, they synchronized the sign of the wave and the synchrotron light pulses. This system enables researchers to record the images (frames) of the sample when the wave was crossing it, giving them the chance to study in detail the fast processes that occur at 500 MHz (500 million times per second).
The results showed that magnetic squares changed the properties under the effect of the waves, widening or narrowing the magnetic dominion depending on the phase of the wave. The deformation does not have an instant effect but a delay between the wave and the magnetic changes.
Understanding how to modify magnetic properties in a fast time scale is crucial to design efficient devices in the future.
Reference: M. Foerster, F. Macià, N. Statuto, S. Finizio, A. Hernández-Mínguez, S. Lendínez, P. Santos, J. Fontcuberta, J. M. Hernàndez, M. Kläui, L. Aballe. “Direct imaging of delayed magneto dynamic modes induced by surface acoustic waves”. Nature Communications, Setembre 2017. DOI: 10.1038/s41467-017-00456-0.