Electrons can be elusive, but Cornell researchers using a new computational method can now account for where they go—or don't go—in certain layered materials.
Physics and engineering researchers have confirmed that in certain quantum materials, known as "misfits" because their crystal structures don't align perfectly—picture LEGOs where one layer has a square grid and the other a hexagonal grid—electrons mostly stay in their home layers.
This discovery, important for designing materials with quantum properties including superconductivity, overturns a long-standing assumption. For years, scientists believed that large shifts in energy bands in certain misfit materials meant electrons were physically moving from one layer to the other. But the Cornell researchers have found that chemical bonding between the mismatched layers causes electrons to rearrange in a way that increases the number of high-energy electrons, while few electrons move from one layer to the other.
"This is an important class of materials people are trying to understand," said Tomás Arias, professor of physics and Stephen H. Weiss Presidential Fellow in the College of Arts and Sciences (A&S), principal investigator of the study. "It was a perfect playground for us in terms of showcasing our new ideas about how to develop that understanding. You can't directly answer questions about these materials in any other way other than what we've developed."
Their new computational method is based on the idea that electrons mostly react to only their immediate surroundings. This foundational research could speed design of materials with desirable properties, including devices with powerful electrical cooling abilities.
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