Graphene, the ultra-thin, ultra-strong material made from a single layer of carbon atoms, just got a little more extreme. University of British Columbia (UBC) physicists have been able to create the first ever superconducting graphene sample by coating it with lithium atoms.
Although superconductivity has already been observed in intercalated bulk graphite -- three-dimensional crystals layered with alkali metal atoms, based on the graphite used in pencils -- inducing superconductivity in single-layer graphene has until now eluded scientists.
"Decorating monolayer graphene with a layer of lithium atoms enhances the graphene's electron-phonon coupling to the point where superconductivity can be induced," says Andrea Damascelli, director of UBC's Quantum Matter Institute and lead scientist of the Proceedings of the National Academy of Sciences study outlining the discovery.
Graphene, roughly 200 times stronger than steel by weight, is a single layer of carbon atoms arranged in a honeycomb pattern. Along with studying its extreme physical properties, scientists eventually hope to make very fast transistors, semiconductors, sensors and transparent electrodes using graphene.
"This is an amazing material,'" says Bart Ludbrook, first author on the PNAS paper and a former PhD researcher in Damascelli's group at UBC. "Decorating monolayer graphene with a layer of lithium atoms enhances the graphene's electron-phonon coupling to the point where superconductivity can be stabilized."
Given the massive scientific and technological interest, the ability to induce superconductivity in single-layer graphene promises to have significant cross-disciplinary impacts. According to financial reports, the global market for graphene reached $9 million in 2014 with most sales in the semiconductor, electronics, battery, energy, and composites industries.
The researchers, which include colleagues at the Max Planck Institute for Solid State Research through the joint Max-Planck-UBC Centre for Quantum Materials, prepared the Li-decorated graphene in ultra-high vacuum conditions and at ultra-low temperatures (5 K or -449 F or -267 C), to achieve this breakthrough.
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