An Ultrathin Electrical Switch Capable of Miniaturizing Computing DevicesApril 17, 2020 by Luke James
Researchers at Berkeley Lab and UC Berkeley have developed an antiferromagnetic switch for computer memory and processing applications that does not compromise on performance.
Researchers have for some time now thought that antiferromagnets—in which the magnetic spins are oppositely aligned to cancel one another out—hold potential as materials that could be used in ultrafast and stable memories. However, nobody has been able to successfully manipulate their magnetization to read and write information in a memory application. That is until now, according to scientists at Berkeley Lab and UC Berkeley.
Researchers working in the Center for Novel Pathways to Quantum Coherence in Materials, a research center funded by the US Government, have developed an antiferromagnetic switch for applications including computer memory and processing.
Their findings, which have been published in the journal Nature Materials, claim that this development could lead to even smaller computing devices and consumer electronics that do not compromise on performance.
Creating an Antiferromagnetic Transition Metal Dichalcogenide
To fabricate their device, the research team used atomically thin sheets of niobium disulfide, a transition metal dichalcogenide (TMD). To form one that is antiferromagnetic, they synthesized layers of iron atoms between each niobium disulfide sheet. Then, by applying small pulses of electrical current, the research team was able to rotate the spins of the antiferromagnet, which in turn switches the material’s resistance from high to low.
The fact that the material can function at ultra-low power means that, in theory, computing devices could be miniaturized without loss of functionality. James Analytis, the head of the research team at UC Berkeley, said that they also found that "these magnetic spins can be flipped or manipulated with small applied currents, around 100 times smaller than those used in any other materials with a similar response,"
A graphic with depicting and measuring the exotic magnetic device developed by researchers at Berkeley Lab and UC Berkeley. The scale shown in the image is 10 micrometers.
Triggering High and Low Resistance States
According to the team’s research paper, the material used, Fe1/3NbS2, consists of layers of the transition metal dichalcogenide NbS2 inserted between iron atoms and exhibits an antiferromagnetic ordering of up to 42 K. It is the application of a pulse along with two orthogonal directions in devices based on Fe1/3NbS2 single crystals that causes the switch from a high- to low-resistance state or vice versa.
These current pulses behave similarly to an in-plane magnetic field, writing a preferred orientation in the antiferromagnetic state. Once switched, the device becomes stable. The AFM’s orientation can then be determined from resistivity measurements, thus enabling it to work as a magnetic memory that can be written and read.
A Whole New Class of Materials
The family of intercalated transition metal dichalcogenides is vast, explains the team’s research, and so it may be possible to identify materials that switch at room temperature based on the same mechanism. This could present a whole new class of materials which, when coupled with the team’s new switching mechanism, could be used as a component for miniaturized computer memory and processing applications.
“In principle, if we could raise the temperature, these (or similar) materials could be used as the basis for magnetic memory storage, with ultra-fast responses and ultra-low powers,” added Analytis. “We plan to try different materials, different elements and perhaps layer different magnetic systems together. So far results look promising.”
Next, the researchers hope to identify a system that operates at room temperature.