Computer technology

New nanoscale device for spintronics

Magneto-optical microscope used for imaging spin waves in a Fabry-Pérot resonator. Credit: Matt Allinson, Aalto University

Spin waves could unlock the next generation of computer technology, a new component allows physicists to control them.

Researchers from Aalto University have developed a new device for spintronics. The results were published in the journal Nature Communicationand mark a step towards the goal of using spintronics to manufacture computer chips and devices for data processing and communication technologies that are small and powerful.

Traditional electronics use electrical charge to perform calculations that power much of our everyday technology. However, engineers are unable to get electronics to perform calculations faster because moving charge creates heat, and we are at the limit of chip size and speed before overheating. Because electronics cannot be made smaller, there is concern that computers cannot become more powerful and cheaper at the same rate as they have been over the past 7 decades. This is where spintronics comes in.

“Spin” is a property of particles like electrons in the same way as “charge”. The researchers are excited to use spin to perform calculations because it avoids the heating problems of current computer chips. “If you use spin waves, that’s spin transfer, you’re not moving charge, so you’re not creating heating,” says Professor Sebastiaan van Dijken, who leads the group that wrote the paper. .

Nanoscale Magnetic Materials

The device made by the team is a Fabry-Pérot resonator, a well-known tool in optics for creating beams of light with a tightly controlled wavelength. The spin-wave version created by the researchers in this work allows them to control and filter spin waves in devices that are only a few hundred nanometers in diameter.

The devices were made by sandwiching very thin layers of materials with exotic magnetic properties on top of each other. This created a device where spin waves in the material would be trapped and canceled if they were not of the desired frequency. “The concept is new, but easy to implement,” says Dr. Huajun Qin, the first author of the paper, “the trick is to make good quality materials, which we have here at Aalto. that it’s not difficult to make these devices means we have plenty of opportunities for exciting new work.

Wireless Data Processing and Analog Computing

Electronics acceleration problems go beyond overheating, they also cause complications in wireless transmission, as wireless signals must be converted from their highest frequencies to frequencies that the electronic circuits can handle. . This conversion slows down the process and requires energy. Spin wave chips are capable of operating at the microwave frequencies used in mobile phone and wifi signals, which means there is a lot of potential for them to be used in even wireless communication technologies. faster and more reliable in the future.

In addition, spin waves can be used to perform calculations faster than electronic computing at specific tasks “Electronic computing uses Boolean or binary logic to perform calculations”, explains Professor van Dijken, “with spin waves of spin, the information is carried in the amplitude of the wave, which allows a more analog calculation. This means that it could be very useful for specific tasks such as image processing or recognition of What’s great about our system is that the size structure of it means it should be easy to integrate into existing technology.”

Now that the team has the resonator to filter and control the spin waves, the next steps are to create a complete circuit for them. “To build a magnetic circuit, we need to be able to guide spin waves to functional components, much like conductive electrical channels on microchips do. We plan to create similar structures to direct spin waves,” says Dr. Qin.

Reference: “Nanoscale magnonic Fabry-Pérot resonator for low-loss spin-wave manipulation” by Huajun Qin, Rasmus B. Holländer, Lukáš Flajšman, Felix Hermann, Rouven Dreyer, Georg Woltersdorf and Sebastiaan van Dijken, April 16, 2021, Nature Communication.
DOI: 10.1038/s41467-021-22520-6

Funding: Academy of Finland, German Research Foundation

The fabrication of the device was carried out at OtaNano.