A University of Arkansas physicist and his colleagues have found that ultra-thin films of superconductors and related materials don’t lose their fundamental properties when built under strain when built as atomically thin layers, an important step towards achieving artificially designed room temperature superconductivity. This ability will allow researchers to create new types of materials and properties and enable exotic electronic phases in ultra-thin films.
Additionally, theorist James Rondinelli at Drexel University, conducted complex super-computer based calculations to determine why the material retains its atomic shape and unique properties. They found that, instead of stretching or compressing, the chemical bonds prefer to rotate to accommodate the strain.
“This opens the door to another whole class of materials and novel magnetic and superconducting phases,” Chakhalian said. Moreover, they discovered that the atomic level strain accommodation creates dramatically different properties depending on the direction of strain, in other words, whether the film is stretched or compressed.
“This gives us another degree of freedom,” Chakhalian said. “This is completely not symmetric, contrary to what everyone has anticipated for decades. And in nanofilms it may end up with absolutely different physics from the bulk crystals.”
This happens because the electrons in high-temperature superconducting and similar materials are keenly aware of one another. This awareness causes them to repel one another to the extreme, so compressing and stretching is not energetically easiest way. Instead, rotation of structural units works best.
“Nature is lazy. It does not want to expend energy,” Chakhalian said. “Now we can use these new-found properties as the foundation of the next generation of ultra-thin film technology with yet unknown functionalities.”