A team of scientists led by the U.S. Department of Energy's (DOE) Argonne National Laboratory has identified a rare, switchable quantum property in a new type of nickel sulfide material. The discovery could have applications in high-speed transistors, adaptive sensors and other devices that require a material's electronic structure to be controlled on the fly. The research is published in the journal Matter.
The compound, KxNi4S2 (0 ≤ x ≤ 1), contains nickel and sulfur sandwiched between layers of potassium. The "(0 ≤ x ≤ 1)" in the name means that the amount of potassium in the material can vary from no potassium at all to a full potassium atom, depending on the sample.
First detailed in a 2021 paper, it was created as part of an ongoing quest to develop more superconductors. As researchers examined the layered material's characteristics, they happened upon a remarkable feature: applying an electrical current could drive the potassium layers out, collapsing the sandwich and changing the material's structure.
This action, which is reversible, allows one material to host two different types of quantum features: Dirac cones and flat band systems.
"You can tune how much potassium comes out of the material, from full to empty and everything in between. This means you can switch from one quantum state to another, all within the same material," said Mercouri Kanatzidis, a professor at Northwestern University with a joint appointment as a materials scientist at Argonne, who led the research.
"I cannot name another material that can do this—if one exists, it is not well known."
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