Long-range information transport in antiferromagnets

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Microscopic magnetic moments in antiferromagnets have their north and south poleMicroscopic magnetic moments in antiferromagnets have their north and south poles alternately - in contrast to those in ferromagnets.

Physicists at JGU discovered: Antiferromagnets are suitable for transporting spin waves over long distances

Smaller, faster, more powerful: The demands on microelectronic devices are high and continue to rise. However, if chips, processors and the like are based on electric current, there are limits to miniaturization. Physicists are therefore working on alternative ways of transporting information. For example, using spin waves, also known as magnons. Their advantage is that they have very low energy losses and therefore propagate over long distances. However, spin waves do not form in just any material, but require certain properties. These are provided, for example, by hematite, the main component of rust.

New class of materials for spin wave transport

Physicists at Johannes Gutenberg University Mainz (JGU) have now been able to develop a completely new class of materials for the transport of spin waves in an EU project together with Université Paris-Saclay, Shanghai University and Grenoble Alpes University: Antiferromagnets with tilted magnetic moments. "These materials have the potential to significantly increase computing speed compared to existing devices while greatly reducing waste heat," says Felix Fuhrmann, a scientist at JGU. This is because spin waves, and thus the information stored in them, can be transported over long distances in the antiferromagnets - around 500 nanometers of distance is possible. While this may not sound like much, transistors in chips today, for example, are usually only about seven nanometers in size, so the range of the spin waves is significantly greater than the distance required. "Transporting information over long distances is crucial for an application in microelectronic devices. With antiferromagnets, we have found a class of materials that offers this important property - opening up a large pool of materials that can be harnessed for devices," Fuhrmann confirms.

An external magnetic field makes it possible

The scientists studied the antiferromagnet yttrium iron oxide, YFeO3. Since its crystal structure differs fundamentally from that of the established hematite, the researchers initially asked themselves: Can spin waves nevertheless form and propagate? Definitely, as the research team discovered. A little trick makes it possible: the physicists apply an external magnetic field to the material. "Magnons are a collective excitation of the magnetic moments in a magnetically ordered crystal - they can therefore be manipulated by magnetic fields, as we were able to successfully demonstrate," says Fuhrmann.

The research was recently published in Nature Communications. Mathias Kläui, who initiated the study in his group, emphasizes: "International collaboration with leading groups within a project funded by the European Union was key to this success."