Scientists from Germany were the first to demonstrate the possibility of storing entire sequences of bits in cylindrical magnetic domains measuring just 100 nanometers. Thanks to this, it will be possible to create new types of data storage and sensors, as well as magnetic devices for creating neural networks.
Image source: hzdr.de
A team of researchers from the Helmholtz Center Dresden-Rossendorf (HZDR), Chemnitz University of Technology, Dresden Technical University and the Jülich Research Center has demonstrated for the first time the possibility of storing not only individual bits, but entire bit sequences in tiny cylindrical nanoregions, TechPowerUp reports.
Professor Olav Hellwig from HZDR explains the concept of a cylindrical magnetic domain, also called a “bubble domain”, as a small cylindrical region in a thin magnetic layer. Its spins, the electrons’ own angular momentum, which creates a magnetic moment in the material, are directed in a certain direction, which leads to the formation of magnetization that is different from the rest of the surrounding environment.
The researchers believe that such magnetic structures have enormous potential for spintronic applications. In this case, the key element is the domain walls formed at the boundaries of the cylindrical domain. It is in these areas that the direction of magnetization changes, which can be used to encode bits of information.
Aiming to overcome the data density limitations of modern hard drives by expanding three-dimensional (3D) storage capabilities, Hellwig’s team used multilayer magnetic structures consisting of alternating layers of cobalt and platinum, separated by layers of ruthenium. These structures were deposited on silicon substrates, forming a synthetic antiferromagnet with a vertical magnetization structure.
Next, the concept of “racetrack” memory was applied, where the bits are arranged along this track like strings of pearls. “The uniqueness of the system we developed lies in the ability to control the thickness of the layers and, consequently, their magnetic properties. This makes it possible to tailor the magnetic behavior of the synthetic antiferromagnet to store not only individual bits, but entire sequences of bits in the form of a depth-dependent direction of domain wall magnetization,” explains Hellwig.
The research results of German scientists open up the prospect of creating new magnetoresistive sensors and spintronic components. In addition, such complex magnetic nanoobjects have great potential for implementation in neural networks, which would help store and process information like the human brain. The results of the work were published in the journal Advanced Electronic Materials.