A new technique for producing and controlling spin waves in nanostructured magnetic materials has been described in a new study that featured as a cover article in the Advanced Materials journal describes.
This study paves the way for creating nano-processors for exceptionally quick and energy-efficient analog processing of information.
The finding was the outcome of a collaborative work by a group of researchers led by Elisa Riedo, Professor of Chemical and Biomolecular Engineering at NYU Tandon School of Engineering; Silvia Tacchi from the Istituto Officina dei Materiali of the Italian National Research Council (CNR-IOM) in Perugia; the magnetism group in the Physics Department at Politecnico di Milano, including Edoardo Albisetti, Daniela Petti, and Riccardo Bertacco; the PolLux Beamline at PSI, in Villigen, Switzerland; and the Physics and Geology Department at University of Perugia.
Spin waves, also called “magnons,” are similar to electromagnetic waves in magnetism. They travel in materials like iron quite similar to waves in the ocean. In contrast to electromagnetic waves, magnons exhibit exclusive properties, making them best suited for building miniaturized “analog” computing systems with considerably more efficiency compared to the existing digital systems.
To date, it was highly challenging to modulate spin waves at will. The paper published in Advanced Materials on March 5th, 2020, describes an innovative type of emitters, known as “magnonic nanoantennas,” which enable generating spin waves with controlled shape and propagation.
For instance, planar wavefronts (similar to ocean waves on the beach) or radial wavefronts (for example, those produced by throwing a stone into a pool of water) can be obtained, and focused directional beams can be created. The study also shows that multiple nanoantennas can be used at the same time to generate interference figures “on command,” which is an essential precondition for creating analog computing systems.
The TAM-SPL technique (developed at Politecnico di Milano partnering with Riedo’s team) was used to achieve the nanoantennas. The technique enables the magnetic properties of the materials to be manipulated at the nanoscale.
Especially, the nanoantennas include minuscule “ripples” in the material’s magnetization (known as “vortices” or “domain walls”) that tend to emit spin waves upon being set in motion under the influence of an oscillating magnetic field.
Since the properties of the spin waves rely on the type and unique characteristics of these ripples, by manipulating them very precisely, the emitted waves could be modulated like never before.
This study was financially supported by the European Union’s Horizon 2020 Research and Innovation Programme, under the Marie Skłodowska-Curie grant No 705326, SWING Project (Patterning Spin-Wave reconfIgurable Nanodevices for loGics and computing).