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Visualize how magnetism surfs

Using ALBA’s synchrotron light, researchers have been able to see acoustic deformation waves in crystals and measure their effect on nanomagnetic elements. The study, published in Nature Communications, uses the temporal structure of the accelerator to record images with a temporal resolution of 80 picoseconds. This methodology offers a new approach for the analysis of dynamic deformations in other fields of research: nanoparticles, chemical reactions, crystallography, etc.

Controlling the magnetic properties of materials is fundamental for developing new memories, computer equipment and other communication devices at the nanometer level. Data storage and processing is progressing so rapidly that different methods need to be tried to modify the magnetic properties of the materials. One way is based on the elastic deformation of the magnetic material to modify its magnetic properties. It allows to write small magnetic elements with an electric voltage instead of current and, therefore, to avoid the losses of energy. However, studies to date have been made at very slow time scales (from seconds to milliseconds).

Another way to produce rapid changes in deformation (at a subnanosecond level) and, therefore, to induce magnetization changes is by using surface acoustic waves (SAWs), which are deformation waves. Imagine an iron rod being struck with a hammer at one end. In doing so, a wave propagates the deformation along the bar. Similarly, a surface acoustic wave propagates a deformation but only in the surface layer, in a way similar to what the waves do in the ocean. In certain (piezoelectric) materials, which expand or contract by applying a voltage, these waves can be generated by oscillating electric fields.

 

A group of researchers from the ALBA Synchrotron, the Materials Science Institute of Barcelona (ICMAB-CSIC) and the University of Barcelona (UB), in collaboration with the Paul Scherrer Institute (Switzerland), Johannes Gutenberg Mainz University and Paul Drude Institute (both in Germany), have developed a new experimental technique to quantitatively visualize these surface acoustic waves and use them to modify the magnetization of magnetic nano-elements (the ‘surfer’) on the surface layer of the crystal. This system could be used to study other areas such as the manipulation of nanoparticles and cells or to control chemical reactions.

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