Being able to use antiferromagnets will make computer memory that is more energy efficient and smaller, faster with less corruption issues. Researchers at the Nanyang Technological University, Singapore (NTU Singapore) have discovered a new way of reading data in antiferromagnets. There were no practical methods to read data from antiferromagnets.
Computer memory traditionally comprises silicon microchips. But in the past few decades, researchers have been looking at using magnetic materials called ferromagnets, made from alloys of cobalt and iron, for memory chips, and that are now used in artificial intelligence and space applications. This is partly because ferromagnetic chips are more energy efficient than silicon ones.
Unique voltage solves data-reading problem
While studying the physical properties of a new antiferromagnetic material called manganese bismuth telluride, Assoc Prof Gao’s team stumbled on an observation that solved the data-reading problem.
They passed an alternating current through a very tiny device the size of a raindrop consisting of manganese bismuth telluride crystal flakes at extremely low temperatures of around 5 Kelvins or -268 degrees Celsius, which approaches the coldness of outer space.
They found a unique voltage signal across the crystals with a frequency double that of the alternating current. The scientists had expected the frequencies of the voltage and current to be the same.
They also found that depending on how the antiferromagnetic manganese bismuth telluride was configured, the sign of the voltage would change.
If the voltage was positive, it meant the antiferromagnet was in a state representing 0.
If the voltage was negative, the material was in a state representing 1. This observation solves the problem of not being able to easily read information stored in antiferromagnets.
Other antiferromagnets should display a similar behavior and their next step will be to test such materials that can encode data at room temperature.
Nature – Quantum metric-induced nonlinear transport in a topological antiferromagnet
Abstract
The Berry curvature and quantum metric are the imaginary part and real part, respectively, of the quantum geometric tensor which characterizes the topology of quantum states. The former is known to generate a zoo of important discoveries such as quantum Hall effect and anomalous Hall effect (AHE) while the consequences of the quantum metric have rarely been probed by transport. Here we report the observation of quantum metric-induced nonlinear transport, including both nonlinear AHE and diode-like nonreciprocal longitudinal response, in thin films of a topological antiferromagnet, MnBi2Te4. Our observation reveals that the transverse and longitudinal nonlinear conductivities reverse signs when reversing the antiferromagnetic order, diminish above the Néel temperature, and are insensitive to disorder scattering, thus verifying their origin in the band structure topology. They also flip signs between electron and hole-doped regions, in agreement with theoretical calculations. Our work provides a pathway to probe the quantum metric through nonlinear transport and to design magnetic nonlinear devices.
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So not a breakthrough so much as a new path toward AF MRAM.
The article is misleading because I have seen several research publications in the last decade detailing both write and read methods for both antiferromagnetic and voltage gated/multiferroic memories – it’s not a new concept, this is just a new way of doing it that is not in fact practical at all as it requires ultra low temps with current materials much as with the colossal magnetoresistance effect which STILL doesn’t have representation in the IT space after many years of research, so this new path to reading AF memories could easily be just as impractical without a chance experiment finding the ideal room temp material.
It specifically states that prior to this AF memories were entirely unreadable and nobody had discovered a method to do so. I even did a search to attempt to find an article or paper that contradicted that, and found none. The title is not misleading at all.
They also specifically state that they are now looking at materials that can do the same thing at room temperature, potentially. The principle is the technology breakthrough, not the materials themselves. Even still, liquid nitrogen could easily be used as a coolant. This is also being used in current computer applications with existing technology. Is it going to be in anyone’s office or living room any time soon? Not likely. It does have many commercial and industrial applications, though.
5K is far lower than what liquid nitrogen can provide. It would have to be helium-cooled which makes it impractical for most purposes. Still, I agree that it’s a breakthrough and do hope they’re able to achieve higher temperatures.