Electric signals show magnetic spin waves, which is a signal in fast computing

Today’s computers store information on magnetic hard drives, keeping files safe even when the device is turned on. But to run programs and process information, computers rely on electricity. Every calculation requires the transfer of information between the electric and magnetic systems. This is a significant bottleneck in the speed of modern computing.

Devices that integrate magnetic components directly into computing logic will overcome this limitation and allow computers to perform faster and more efficiently.

A new theoretical study led by University of Delaware engineers reveals that magnus, a type of magnetic spin wave, can produce detectable electrical signals. The results, published in Proceedings of the National Academy of Scienceshighlight possible ways to control and manipulate magnets with electric fields and suggest a path toward integrating electric and magnetic components to enable next-generation computing technologies.

How do magnetic waves carry information?

Magnetism begins with electrons, tiny particles that orbit the nucleus of an atom. Each electron has a property called spin, which can point up or down. In a standard iron ferromagnet, all the turns point in the same direction, creating a magnetic field.

“Imagine that there’s a spring connecting all these spins. If I end one spin, it’s like pulling on the spring. The next spin snaps, then the next, then the next,” said senior author Matthew Doughty, a professor in the Department of Materials Science and Engineering in UD’s College of Engineering. “You can think of it like a slinky: pull it and give it a spin, and a wave spreads out under the coil. A Magon is just that: a wave.”

In today’s computer chips, charged electrons flow through wires, creating resistance and losing a lot of energy as heat. Because magnons transmit information through the direction of rotation, without transferring any electrical charge, they encounter no resistance and dissipate much less energy.

The new research focused on antiferromagnetic materials, which spin. These materials are appealing for computing applications because magnons in antiferromagnets can propagate at terahertz frequencies, which is about a thousand times faster than the speed of magnons in ferromagnets. But since antiferromagnetic materials have zero spin overall, antiferromagnetic magnets are extremely difficult to detect and manipulate.

A way to detect and manipulate magnets

Attention postdoctoral researcher D. Kuang and colleagues used computer simulations to determine how magnons behave in antiferromagnetic materials. To their surprise, calculations revealed that magnon motions could produce electrical signals.

“The results predict that we can detect magnes by measuring the electrical polarization they create,” Doty said. “An even more exciting possibility is that we could use external electric fields, including light, to control magnon motion. Future devices that replace conventional wires with magnon channels could transmit information much faster and with much less wasted energy.”

The team analyzed what happens when one side of a substance is hotter than the other, causing the magnon to flow from hot to cold. In particular, they sought to understand the consequences of magnon orbital angular momentum, a circular motion of magnetic waves that differs from their forward motion.

“We have developed a mathematical framework to understand how the orbital angular momentum plays an important role in magon transport,” said the paper’s first author. “We discovered that when the magnon orbital angular momentum interacts with the atoms in the material, it produces an electric polarization.”

In other words, moving antiferromagnetic magnets can produce a measurable voltage.

“Our framework provides a powerful tool that will allow the research community to predict and manipulate magnon behaviors.”

The UD team has started experiments to confirm the predicted effects. They also plan to explore how magnons interact with light to determine whether light’s orbital angular momentum can be used to transport or detect magnons.