Spintronics: significant progress

An international research team has achieved a breakthrough in atomically thin antiferromagnetic tunnel junctions. This shows the great potential of antiferromagnetic materials for storage technology.

Spintronics (spin electronics) deals with the use of electron spin in electronic devices. In contrast to conventional electronics, which only uses the charge of the electrons, spintronics also uses the spin of the electrons, i.e. a "direction of rotation" at the atomic level, to store and process information. An international team consisting of scientists from the Max Planck Institute of Microstructure Physics in Germany, the University of Nebraska-Lincoln, USA and the JKU (Institute of Theoretical Physics) has now made important progress in this field of research:

Magnetic tunnel junctions (MTJs) are a key component of spintronic memory technology. They enable highly sensitive magnetic field sensors used in all magnetic hard disk drives (which store 70% of all digital data) and non-volatile magnetic memories that offer high levels of performance, reliability and scalability beyond today’s charge-based memories.

A classical MTJ structure consists of a non-magnetic tunnel barrier enclosed by two ferromagnetic electrodes. The underlying mechanism is the spin filter effect for the spin-polarized charge current generated by passing through the ferromagnetic electrodes. However, there are two challenges with spintronic MTJs for practical applications: a relatively slow operating speed and stray field interference due to the properties of ferromagnetic materials. Antiferromagnets, on the other hand, are more robust against various interferences and thus have great potential for spintronic applications. They are considered key to the next generation of storage technologies as they offer ultra-fast and interference-free properties.

The research team, led by Stuart Parkin from the Max Planck Institute of Microstructure Physics in Germany, has now developed a revolutionary atomically thin antiferromagnetic tunnel junction made by twisting two-dimensional (2D) materials in their study published in the prestigious journal Nature. As part of the study, a novel technique was developed in which two double layers of the 2D antiferromagnet CrSBr were twisted.

The researchers discovered that the performance varied depending on the angle of rotation. Arthur Ernst from the JKU Institute of Theoretical Physics was part of the research team and can explain this effect: ,,The magnetic interaction between layers takes place through bromine. Bromine is not magnetic, but it is important for the spin transport between chromium from two neighboring layers. During rotation, this interaction is weakened or, in certain cases, strengthened. This makes it possible to manipulate the magnetic properties of such a contact. This could be of great importance for future spintronic applications. "

The researchers investigated the effects of different twist angles on the performance of the tunnel junctions and found that the magnetic properties can be greatly altered by the twist. They also noticed that the temperature dependence of the magnetic properties is much lower for the twisted junctions than for the untwisted ones, which further improves their potential applications. This discovery could be used not only in computer and memory technology, but also in the development of new types of sensors and other electronic components.