The atoms within individual two-dimensional layers of tantalum sulfide are shown in the electron microscopy image. All layers are bonded with geometry before heat-treating. Most layers are bonded with geometry after heat-treating. The remaining layers have switched from conductor to insulator. The bar is two nanometers in size. The University of Michigan has a credit card.
The University of Michigan has developed a semiconducting material that can flip from a conductor to an above room temperature. It could bring the world closer to a new generation of quantum devices.
The exotic electronic structure that supported this quantum flip was only stable at ultra-cold temperatures. The material is stable at up to 170 degrees.
"We've opened up a new playground for the future of electronic and quantum materials," said Robert Hovden, a U-M assistant professor of materials science and engineering and corresponding author on the paper in Nature Communications. It is a new way to access exotic states.
The ability to switch from a conductor to an insulator could be key to the next generation of computing. That could lead to more powerful devices.
The data disappears when the power is turned off, because today's electronics use tiny electronic switches to store data. Future devices could use other states, like "conductor" or "insulator", to store digital data, requiring only a quick blip of energy to switch between states.
Exotic behavior has only been observed in materials that are very cold. The ultimate goal is to develop materials that can flip from one state to another on demand and at room temperature. The research could be an important step in that direction.
He said that previous research has shown that it's possible to make these kinds of flips happen on demand. "That wasn't the focus of this project, but the fact that we were able to keep one flip stable at room temperature opens a lot of exciting possibilities."
During the heat-treating process, the layers of tantalum sulfide are converted into a prismatic state. The University of Michigan has a credit card.
A charge density wave is a phenomenon that1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556
The material had to be at ultra-cold temperatures to have charge density waves. We were able to make it more stable by interleaving several two-dimensional layers together.
The team started by making a sample of several layers of tantalum sulfide. A specific arrangement of tantalum and sulfur atoms is what's referred to as an octahedral state. There were some charge density waves present, but they were too unstable and disorganized to give rise to exotic behavior.
The sample's properties were changed by heating it in an oxygen-free environment and observing the process under an electron microscope by the first author on the paper. As the sample heated, layers began to change into a different arrangement of the same atoms.
The sample was cooled back to room temperature when most of the layers switched to prismatic state. He found that the layers that remained in the octahedral state exhibited charge density waves that were orderly and stable, and stayed that way at temperatures up to 170 degrees Fahrenheit. The layers had flipped from semiconductors to insulators.
Most 2D materials are subject to all the defects of whatever they're sitting on, whatever's in the air, and that makes them very unstable. When the layers are nestled between the other layers, they are more stable.
The team is looking at the phenomenon further, tweaking more variables of the process and testing mechanisms to control the exotic behaviors spurred by the charge density waves. The new discovery has given them a glimpse into the workings of quantum states and two-dimensional materials.
The two-dimensional charge order is stable in clean polytype Heterostructures. There is a DOI: 10.1038/s41467-021-27947-5.
Nature Communications is a journal.
The news about quantum tech was retrieved fromphys.org on January 20, 2022.
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