When ice melts into water, it changes. It behaves differently, it moves differently, and the atoms are organized differently. These are all effects of a phase change, and while they don’t change what a material is, they can definitely change how it works.
The same thing—or at least a similar thing—happens in the quantum realm, and these quantum phase changes are extremely interested to researchers studying superconductors. “How a superconducting phase can be changed to another phase is an intriguing area of study,” Sanfeng Wu, who studies these transitions, said in a press release. “And we have been interested in this problem in atomically thin, clean, and single crystalline materials for a while.”
In order to turn that interest into more scientific knowledge, as the research team describes in a study recently published in the journal Nature Physics, they turned to a material known as tungsten ditelluride and shaved it down until it was just three atoms thick. Then, they made it cold. Really cold. -459.58 F° cold.
One it was cold enough, the team added a few extra electrons to the material and made themselves a superconductor. “Just a tiny amount of gate voltage can change the material from an insulator to a superconductor,” Tiancheng Song, lead author of the paper, said in a press release. “This is really a remarkable effect.”
But it wasn’t the only remarkable effect. It turns out that at certain electron densities, something really weird happened—something the team was really not expecting.
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