Antiferromagnetic memories allow higher data volume and faster write speed.

http://www.smart2zero.com/news/writing-speed-terahertz

With a frequency of several terabits per second, data rushes through the fiber optic cables. Once they arrive at the PC or television, data processing only continues at the speed of the electronic components - currently just several hundred gigabits per second. Researchers at the University of Mainz (JGU) have developed a technology that can increase data processing speed a hundredfold and close the gap between transport and processing speed. 
In the future, bandwidths that are too low could be a thing of the past: Researchers from the Academy of Sciences of the Czech Republic, together with their colleagues from JGU, have discovered a way to drastically increase the speed of data processing. To be more precise: a hundred times, on a terahertz.

To understand the background, first an excursion to the principle of magnetic storage. Usually magnetic data storage devices are based on ferromagnetic materials. However, these have limits in two respects: On the one hand, the data cannot be packed as tightly as you like, and the capacity of the memory reaches a natural limit. The data is stored in a kind of tiny bar magnet, which symbolizes a zero or a one, depending on the orientation. However, if these "rod magnets" are too close to each other, they influence each other. On the other hand, the speed at which these data memories can be written is limited. It doesn't get any faster than in the gigahertz range - otherwise the energy consumption will be immense.

The situation is different with antiferromagnetic storage devices. They can be described much more densely - because the "rod magnets" are always alternately aligned here and thus do not influence each other. This means that considerably more data can be stored on it. On the other hand, they solve the problem of limited writing speed.

"If data is to be sent, light is used which is sent via optical fibre cables," explains

professor Jairo Sinova, head of the "Interdisciplinary Spintronics Research" group at JGU. "This is extremely fast with frequencies in the terahertz range. At present, this speed must be reduced for processing in computers or televisions, where data is processed and stored electrically at speeds of several hundred gigahertz. The antiferromagnetic memories are now able to work directly with the data in the terahertz range for the first time". With this technology, the signal on the device no longer needs to be slowed down, but can also be processed on the computer or TV at terahertz speed.

The first research was carried out in 2014, when the scientists sent an electric current through the antiferromagnets to align the small storage units. They used a copper cable - a slow connection method. Instead, they use a short laser pulse to induce an electric current. This current aligns the'rod magnets', i.e. the spins. In this way, the researchers were able to drastically increase the speed.