Faster and more efficient information transfer using antiferromagnetic rust

An electric current excites the overlap of two magnons with linear polarization (indicated by the red and blue arrows). The energy is then transported through the antiferromagnetic insulator. This can be detected as electrical voltage. Credit: Ill./ ©: Andrew Ross, JGU

Physicists use antiferromagnetic rust to carry information over long distances at room temperature.

Whether with smartphones, laptops or mainframes: Transmitting, processing and storing information is currently based on a single class of material – as it was in the early days of computer science about 60 years ago. However, a new class of magnetic materials can take information technology to the next level. Antiferromagnetic insulators enable computational speeds that are a thousand times faster than conventional electronics, with significantly less heat. The components can be packed closer together and the logic modules can be made smaller, which so far has been limited due to the increased heat of the current components.

Transfer of information to room temperature

So far, the problem has been that the transfer of information to antiferromagnetic insulators has only worked at low temperatures. But who wants to put their smartphones in the fridge to be able to use them? Physicists at Johannes Gutenberg University in Mainz (JGU) have now been able to eliminate this shortcoming, along with experimenters from the CNRS / Thales lab, CEA Grenoble and the National High Field Laboratory in France, as well as theorists from the Center for Spintronics Quantum (QuSpin) at the Norwegian University of Science and Technology. “We were able to transmit and process information in a standard antiferromagnetic insulator at room temperature – and do it long enough to allow information to happen,” said JGU scientist Andrew Ross. The researchers used iron oxide (α-Fe2O3), the main component of rust, as an antiferromagnetic insulator, because iron oxide is diffuse and easy to produce.

The transfer of information to magnetic insulators is made possible by the excitation of the magnetic order known as the magnone. These move like waves through magnetic materials, similar to how waves move across the water surface of a basin after a rock is thrown into it. Previously, it was believed that these waves had to have circular polarization in order to transmit information efficiently. In iron oxide, such circular polarization occurs only at low temperatures. However, the international research team was able to transmit magnons over extremely long distances even at room temperature. But how did it work? “We realized that in single-plane antiferromagnets, two magnets with linear polarization can overlap and migrate together. They complement each other to form a circular circular polarization, ”explained Dr. Romain Lebrun, a researcher at the joint CNRS / Thales laboratory in Paris, who previously worked in Mainz. “The possibility of using iron oxide at room temperature makes it an ideal playground for the development of ultra-fast spinning devices based on antiferromagnetic insulators.”

Extremely low attenuation allows for efficient energy transmission

An important question in the information transfer process is how quickly information is lost when moving through magnetic materials. This can be quantified by the magnetic damping value. “The iron oxide examined has one of the lowest magnetic attenuations ever reported in magnetic materials,” explained Professor Mathias Kläui of the JGU Institute of Physics. “We anticipate that high magnetic field techniques will show that other antiferromagnetic materials have equally low attenuation, which is essential for the development of a new generation of spintronic devices. We are pursuing such low power magnetic technologies in a long-term collaboration with our colleagues at QuSpin in Norway and I am happy to see that another piece of exciting work has emerged from this collaboration. “

Reference: “Long-distance rotational transport through the Morin phase transition to room temperature in single ultra-low antiferromagnet α-Fe damping crystals2O3”By R. Lebrun, A. Ross, O. Gomonay, V. Baltz, U. Ebels, A.-L. Barra, A. Qaiumzadeh, A. Brataas, J. Sinova and M. Kläui, 10 December 2020, Nature Communications.
DOI: 10.1038 / s41467-020-20155-7

The search was recently published in Nature Communications and was funded by the EU Research and Innovation program Horizon 2020, the German Research Foundation (DFG) and the Norwegian Research Council.

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