Jun 4 2019
People universally stream videos, store large numbers of photos on their devices, and download audiobooks to mobile devices. In brief, the need for more storage capacity is constantly growing. Scientists are aiming to create new data storage options. One option is the racetrack memory device where the data can be stored in nanowires in the form of oppositely magnetized areas, so-called domains. The research findings have recently been reported in the scientific journal Nature Materials.
A recent discovery made by a study team from Johannes Gutenberg University Mainz (JGU) in Germany, together with colleagues from Eindhoven University of Technology in the Netherlands as well as Daegu Gyeongbuk Institute of Science and Technology and Sogang University in South Korea, could considerably enhance these racetrack memory devices. Rather than using individual domains, in the future people could store the information in 3D spin structures, rendering the memories faster and more strong and providing a bigger data capacity.
"We were able to demonstrate a hitherto undiscovered interaction," explained Dr. Kyujoon Lee of Mainz University. "It occurs between two thin magnetic layers separated by a non-magnetic layer." Typically, spins align either parallel or antiparallel to each other. This would also be anticipated for such two individual magnetic layers. However, the circumstances are different in this work as the scientists have been able to demonstrate that in specific systems the spins in the two layers are twisted against each other. More exactly, they couple to be aligned perpendicular at an angle of 90° with one another. This new interlayer coupling interaction was hypothetically explained using theoretical calculations done by the project collaborators at the Peter Grünberg Institute (PGI) and the Institute for Advanced Simulation (IAS) at Forschungszentrum Jülich.
The Mainz-based scientists studied several different combinations of materials grown in multi-layers. They were able to demonstrate that this formerly unknown interaction exists in various systems and can be engineered by the design of the layers. Theoretical calculations allowed them to comprehend the underlying mechanisms of this innovative effect.
With their findings, the scientists expose a missing component in the interaction between such layers. "These results are very interesting to the scientific community in that they show that the missing antisymmetric element of interlayer interaction exists," commented Dr. Dong-Soo Han from JGU. This paves the way for designing numerous new 3D spin structures, which could result in new magnetic storage units in the long run.
I am very happy that this collaborative work in an international team has opened a new path to three-dimensional structures that could become a key enabler for new 3D devices. Through the financial support of the German Research Foundation and the German Academic Exchange Service, the DAAD, we were able to exchange students, staff, and professors with our foreign partners in order to realize this exciting work.
Mathias Kläui, Study Senior Author and Professor, University of Mainz