Magnetic storms pave the way for energy-efficient computing

Researchers at the Johannes Gutenberg University in Mainz and the University of Konstanz in Germany as well as the Tohoku University in Japan have managed to increase the distribution of magnetic particles, called skyrmions, by a factor of 10. Their results are published in the magazine. Nature Communication.

In today’s world, our life is unimaginable without computers. So far, these devices process information using electrons primarily as charge carriers, and the materials themselves heat up a lot in the process. Efficient cooling is therefore necessary, which comes with high energy costs.

Spintronics aims to solve this problem. Instead of using the flow of electrons for information processing, it relies on their spin or internal angular momentum. This method is expected to have a positive impact on the size, speed, and stability of computers or certain components.

Magnetic storms store and transmit information

Science often looks not just at the spins of individual electrons, but rather at the magnetic whirls made up of multiple spins. These whirls, called skyrmions, arise from a thin magnetic layer and can be thought of as two-dimensional particles. On the other hand, the whirls can be moved deliberately by applying a small amount of electricity to small parts; on the other hand, they move randomly and extremely perfectly due to diffusion.

The ability to create a functional computer based on skyrmions has been demonstrated by a group of researchers from the Johannes Gutenberg University of Mainz (JGU), led by Professor Dr. Mathias Kläui, using the first prototype. This display consisted of thin, stacked layers of metal, some only a few atomic layers apart.

Energy efficiency: 10 times increase in whirl diffusion

In collaboration with the University of Konstanz and Tohoku University in Japan, researchers at the University of Mainz have now achieved another step towards spin-based, forbidden computing.

They were able to increase the dispersion of the sky by a factor of about 10 using synthetic antiferromagnets, which greatly reduces energy consumption and increases the speed of the potential computer. “Reducing energy consumption in electronic devices is one of the biggest problems in basic research,” emphasized Professor Dr. Ulrich Nowak, who led the theoretical part of the project in Konstanz.

But what is an antiferromagnet and what is it used for? Conventional ferromagnets consist of many small coils, all joined together to point in the same direction, thus creating a large magnetic moment.

In antiferromagnets, the spins are arranged alternately antiparallel, ie, the spin and its direct neighbors point in the opposite direction. As a result, there is no magnetic moment, although the spins remain antiferromagnetically well ordered. Antiferromagnets have important advantages, such as three dimensions of fast switching dynamics, better stability, and the possibility of high storage density. These structures are studied intensively in many research projects.

Advantages of synthetic antiferromagnets

To understand why these antiferromagnets are useful in this context, we need to look deeper. When skyrmions move very fast, an additional energy component arises from the ferromagnetic layer perpendicular to the direction of motion. This force field pushes the skyrmions out of the way.

As a result, they end up bumping into the wall, get stuck, and block the way for others. At high speeds, they can even be destroyed. However, it is theoretically known that this effect either does not occur in antiferromagnets or occurs to a very small extent.

To create an antiferromagnet, the researchers combined two of their ferromagnetic layers in such a way that the magnets in the two layers are aligned precisely in opposite directions, canceling their magnetic fields. This provides two benefits: They reduce the force pushing the storms along their path and thereby increase dispersion.

“With this, we have created an artificial antiferromagnet in which the dispersion of skyrmions is ten times greater than one standard,” said Klaus Raab, a physicist at JGU. “This spread can be implemented to implement stochastic computing – a method of computing in which stochastic processes such as the random movement of particles are used.”

A team of researchers investigated the effect of the compensation of magnetic layers in addition to the effect of temperature and size of the sky on the distribution and therefore on the movement of skyrmions, both experimentally and by simulation. A complex connection was found.

As the temperature increases, the skyrmions have more ability to spread rapidly. Heat also reduces the size of skyrmions, which positively affects their movement. Vertical power sector compensation also has a positive effect on distribution. All these results are difficult to separate from each other. “The increase in diffusion appears to be due not only to the pure magnetic flux but also to the corresponding reduction in the size of the sky,” summarized Raab.