Creating and deleting skyrmions using mechanical stimulus. Image: RIKEN.
Creating and deleting skyrmions using mechanical stimulus. Image: RIKEN.

In a study published in Nature Communications, scientists from the RIKEN Center for Emergent Matter Science in Japan have found a way to manipulate skyrmions – tiny nanometer-sized magnetic vortices found at the surface of magnetic materials – using mechanical energy.

Skyrmions have been widely touted as providing the basis for new high-density memory devices because of their small size and relative stability. However, it has proven difficult to create, delete and move them, and so skyrmion-based devices are not yet competitive with other next-generation memory devices based on electron spin.

According to Yoichi Nii of the Emergent Device Research Team, the first author of the study: "We began from the simple question of whether it would be practical to turn skyrmions on and off with mechanical force, and wondered how much force would be required. We imagined it would be substantial."

The group set out to answer this question using a specially-designed stress probe that could apply mechanical stress to the surface of manganese silicide, a ‘chiral magnetic’ known to host skyrmions, cooled to very low temperatures. They found, to their surprise, that the force required to create and delete skyrmions was quite low, less than ten nanonewtons per skyrmion, comparable to the pressure exerted by the tip of a conventional pencil when writing in a notebook. A force applied perpendicular to the magnetic field led to the creation of skyrmions, while a force applied parallel to the field deleted the skyrmions, making it possible to turn them on and off mechanically.

“This means,” says Yoshihiro Iwasa, leader of the Emergent Device Research Team, “that we may be able to fabricate devices in which skyrmions are created and deleted by a small mechanical force. This could be an inexpensive and low-energy-consuming way to create new low-cost memory devices and open the road to skymionics.”

One drawback of the current approach is that it requires cooling the magnet to very low temperatures for the system to work. According to Nii, they plan to continue experiments with a variety of materials to try to identify ones that host skyrmions that can be manipulated mechanically at higher temperatures.

The work was done in collaboration with the University of Tokyo, the Japan Proton Accelerator Research Complex and the Comprehensive Research Organization for Science and Society.

This story is adapted from material from RIKEN, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.