A new state of matter Discovered accidentally by Physicist

Credit: Hannah Moore/Northeastern University

Physicists at Northeastern have discovered a new way to manipulate electric charge. And the changes to the future of our technology could be monumental.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.

The phenomenon appeared while the researchers were running experiments with crystalline materials that are only a few atoms thick, known as 2-D materials. These materials are made up of a repeating pattern of atoms, like an endless checkerboard, and are so thin that the electrons in them can only move in two dimensions.

Physicist were examining two such 2-D materials, bismuth selenide and a transition metal dichalcogenide, layered on top of each other like sheets of paper.

Electrons should repel one another they’re negatively charged, and move away from other negatively charged things. But that’s not what the electrons in these layers were doing. They were forming a stationary pattern.

The crystalline structures of 2-D materials are too small to observe directly, so physicists use special microscopes that fire beams of electrons instead of light. As the electrons pass through the material, they interfere with each other and create a pattern. The specific pattern (and a bunch of math) can be used to recreate the shape of the 2-D material.

When the resulting pattern revealed a third layer that couldn’t be coming from either of the other two, Physicist thought something had gone wrong in the creation of the material or in the measurement process. Similar phenomena have been observed before, but only at extremely low temperatures. Kar’s observations were at room temperature.

But after repeated testing and experiments their results remained the same. There was a new lattice-style pattern of charged spots appearing between the 2-D materials. And that pattern changed with the orientation of the two sandwiching layers.

When two repeating patterns or grids are offset, they combine to create a new pattern (you can replicate this at home by overlapping the teeth of two flat combs). Each 2-D material has a repeating structure, and the researchers demonstrated that the pattern created when those materials are stacked determines where electrons will end up. 

“That is where it becomes quantum mechanically favorable for the puddles to reside,” physicist says. “It’s almost guiding those electron puddles to remain there and nowhere else. It is fascinating.”

Understanding of this phenomenon is still in its infancy, it has the potential to impact the future of electronics, sensing and detection systems, and information processing. 

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