State Research Center OPTIMAS

Magneto-acoustic waves: Around two million euros for information processing with spin and sound

Professor Dr. Mathias Weiler. Photo by TUK/Koziel

Professor Dr. Mathias Weiler from the Technische Universität Kaiserslautern (TUK) has been awarded a Consolidator Grant by the European Research Council (ERC). He will receive around two million euros over the next five years. Weiler and his team are working on spin waves and new spintronic devices that could significantly accelerate the storage, processing and transmission of information. A major challenge here is the control of magnetic materials with complex spin order. With the funding, Weiler now wants to use surface acoustic waves for this purpose, which have so far been used primarily in our smartphones.

When processing information, we primarily use the electrical charge of electrons. However, devices are becoming ever smaller and more powerful. Electric current with its high waste heat is reaching its limits here. That's why scientists are working on alternatives, such as the use of spin waves. "Spin describes the intrinsic angular momentum of a quantum particle, for example  an electron or neutron," says Professor Dr. Mathias Weiler, who conducts research on applied spin phenomena at TU Kaiserslautern. "It forms the basis for all magnetic phenomena."

Collective excitations of spins - so-called spin waves - can transport more information than electrons while consuming significantly less energy and generating less waste heat. This makes spin waves interesting for applications. They could be used to develop new spintronic devices that significantly accelerate the processing and storage of information.

An important role is played by magnetic materials that have complex spin orders and associated special properties. Such complex spin orders are found in antiferromagnets and magnetic skyrmions. "Unlike ferromagnets, which have wide technological applications as permanent magnets, complex magnetic materials cannot be characterized by an easily controllable macroscopic magnetization," Weiler says. "Instead, their complex spin structure is protected by quantum mechanical exchange interaction and topology, so it cannot be easily perturbed by external magnetic fields." This protection, along with natural frequencies that can reach the terahertz range, makes complex spin systems particularly suitable for robust and fast information processing.

So far, however, no efficient methods exist to control spin waves in these systems. The potential of this class of materials therefore remains largely untapped. This is where the EU-funded project "Magneto-Acoustic Waves in Complex Spin Systems" (MAWiCS) comes in: Mathias Weiler's team aims to combine complex spin systems with surface acoustic waves (SAW). "Surface acoustic waves are widely used in communication technology. They are used, for example, to realize the numerous frequency filters in smartphones," the physicist from Kaiserslautern continues. "We will link this current key technology with next-generation spin-based information technology."

The physicists take advantage of the fact that SAWs couple very well to these complex spin systems and thus can control them very efficiently. Weiler's group thereby benefits from its long-standing expertise in using SAWs to control ferromagnetic systems. The team will now extend this expertise to antiferromagnets and chiral magnets. "With our experiments, we want to lay the groundwork for these materials to come into use in information processing," Weiler summarizes. "They can enable a new class of information technology."

The work will take place in the new research building LASE (Laboratory for Advanced Spin Engineering) on the TUK campus. The group's research is integrated into the Rhineland-Palatinate-funded state research center OPTIMAS (Optics and Materials Sciences), the TopDyn research initiative established jointly with the Johannes Gutenberg University Mainz, as well as the priority program SPP 2137 "Skyrmionics: Topological spin phenomena in real space for applications" and the collaborative research center SFB/TRR 173 "Spin+X - Spin in its collective environment", which are funded by the German Research Foundation.

Contact:
Professor Dr. Mathias Weiler
Applied Spin Phenomena / Department of Physics
Phone: +49 (0)631 205-4099
E-Mail: weiler(at)physik.uni-kl.de

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