Gone are the days when the classical states of matter (solid, liquid, gas, plasma) were all that mattered. Many new complex states, including Bose-Einstein condensates and neutron-degenerate matter, have been observed, often under extreme conditions. However, a team of researchers at Northeastern University, Boston, may have accidentally stumbled upon the latest matter to matter at room temperature. This material provides a new way to manipulate electric charge, posing new possibilities for the future of modern technology.
“I’m tempted to say it’s almost like a new phase of matter, because it’s just purely electronic,” Swastik Kar, an associate professor of physics at Northeastern and co-author of the paper describing the new matter, said in a statement. “It could change the way we can detect and communicate signals. It could change the way we can sense things and the storage of information, and possibilities that we may not have even thought of yet.”
Kar and his colleagues were toying with ultra-thin layers of 2D materials, which are only a few atoms thick, when the discovery happened. In this instance, they had stacked a layer of bismuth selenide on top of a layer of the transition metal dichalcogenide. Instead of the electrons in the material repelling one another, as expected, they actually formed a stationary electronic lattice-style pattern between the two layers.
“At certain angles, these materials seem to form a way to share their electrons that ends up forming this geometrically periodic third lattice,” Kar said, whose team’s results were published in Nanoscale. “A perfectly repeatable array of pure electronic puddles that resides between the two layers.”
Even after verifying the discovery through electron microscopy, Kar was still sure a mistake had been made, as similar phenomena had only been observed at extremely low temperatures, never at room temperature like this discovery.
“Have you ever walked into a meadow and seen an apple tree with mangoes hanging from it?” Kar asks. “Of course we thought something was wrong. This couldn’t be happening.”
Repeated testing and experiments yielded the same results, which sprung other researchers into action to understand how this lattice-style pattern of charged spots was theoretically possible. They found that the arrangement of the 2D layers, along with quantum mechanical factors, generated holes, which in turn enabled the production of puddles of charge.
“They produce these regions where there are, if you like, ditches of some kind in the potential landscape, which are enough to force these electrons to create these puddles of charge,” Arun Bansil, a university distinguished professor of physics at Northeastern, explained in a statement. “The only reason electrons will form into puddles is because there’s a potential hole there.”
Although they are in the early stages of understanding this phenomenon, the researchers are excited about the possible impact it could have on the future of electronics, sensing and detection systems, and information processing.
“The excitement at this point is in being able to potentially demonstrate something that people have never thought could exist at room temperature before,” Kar said. “And now, the sky’s the limit in terms of how we can harness it.”