Antiferromagnetic Rust Transmits Data


Ray Ma, Staff Writer

For the past 56 years, the material we have used to transmit and store information on our devices has largely stayed the same. More recently, however, scientists have begun exploring a new class of magnetic materials called antiferromagnetic insulators, which can significantly increase computing speeds. 

Antiferromagnetic insulators store and transmit data. Materials such as iron oxide or nickel oxide are antiferromagnetic as they have microscopic magnets with opposite orientations of electron spins, in contrast to ferromagnets, which align parallel in magnetic domains.

Each bit of data can be represented by the thousands of atoms that align into groups called domains, which are tiny bar magnets within the magnet itself. Unlike in antiferromagnetic material, the domains in the ferromagnetic material exert conflicting influences on each other, so scientists have a preference for the former.

Data is sent through antiferromagnetic insulators via the excitations, or “magnons,” of the domains. Magnons move like waves through the materials, similar to how ripples move on the surface of water after a stone has been dropped. The energy being transported through the magnons can be read as voltages.

For a long time, scientists believed that magnons must have something called “circular polarization” to transmit information. Circular polarization occurs when these waves travel both the horizontal and vertical plane, as well as all the planes in between, creating a radial pattern.

Since waves with circular polarization are achievable only in low-temperature settings, this posed a problem for researchers: how could they make antiferromagnetic insulators functional at higher temperatures?

To solve this problem, the physicists at Johannes Gutenberg University Mainz worked in collaboration with several other researchers located at the Center for Quantum Spintronics (QuSpin), the Norwegian University of Science and Technology, and laboratories in France such as the National High Field Laboratory.

The researchers chose iron oxide (rust) because of its ability to retain the information as the magnons move through the material, which is unique from other antiferromagnets. The commonality of rust and the ease of manufacture makes it an extremely viable candidate for future use.

In the experiment, the researchers disproved the previous belief that the magnons must have a circular polarization to transmit information, as two magnons with linear polarizations (which move in a defined singular plane in the direction of propagation) could overlap and create a close approximation to a true circular polarization.

This discovery negated the need for the materials to be stored in freezing temperatures in order for antiferromagnetic insulators to function. 

Dr. Romain Lebrun, a researcher at Unité Mixte de Physique CNRS/Thales, and other researchers were able to transmit and process information at room temperature and at long distances, proving that the antiferromagnetic insulators could be implemented in data transmission. 

With the restriction overcome, Dr. Romain Lebrun from the JGU Institute of Physics believes that “devices based on fast antiferromagnet insulators are now conceivable.”