UI physicists have fabricated arrays of sub-micron-sized superconducting "islands" on metallic films and used them to study changes in the transition to superconductivity based on island spacing and thickness. They discovered that such systems may be an ideal medium for understanding and controlling the properties of a theoretically forbidden zero-temperature metallic state. Read their paper in Nature Physics. High-resolution image.
Written by Serena Eley and Celia Elliott
In 1958, Dr. Philip Anderson, a future Nobel Laureate, made a groundbreaking prediction. At zero temperature in 1D and 2D solids, the diffusive motion of electrons scattering off impurities ceases, and there is no long range electron transport. In other words, 1D and 2D systems no longer conduct like standard metals at zero-temperature. Although this theory has accurately described the low-temperature behavior of many materials, systems ranging from 2D semiconductors to disordered superconductors have in fact shown evidence of this forbidden zero-temperature metallic state.
Determining the origin and characteristics of such metals has attracted intense theoretical and experimental interest over the past two decades. Contributing to these efforts, the Mason research group at the University of Illinois focuses on novel model systems of 2D superconductors, systems which have been predicted to exhibit these unusual metallic states as the temperature approaches zero.
"In particular, we created arrays of physically separated superconducting islands placed on normal metal films, and measured the temperature-dependent transition to the superconducting state as a function of the island separation," said graduate student Serena Eley.
"We found two surprising results: first, the long-range communication between the islands occurs in a way that cannot be explained by current theories. Second, the progressive weakening of superconductivity with increasing island spacing suggests that arrays with even further spacing would be metallic at zero temperature."
Serena Eley, Sarang Gopalakrishnan, and Nadya Mason in their lab at the University of Illinois. Not shown is co-author Paul M. Goldbart, Georgia Tech. The work reported by the UI group in a recent paper in Nature Physics is the first study of an inhomogeneous superconducting system that systematically approaches a zero-temperature metallic state. Furthermore, the results suggest that such superconductor-normal-metal systems may be an ideal medium for tunably controlling the properties of this strange metal.
Madeline Stover is a physics doctoral student at the University of Illinois Urbana-Champaign studying atmospheric dynamics applied to forest conservation. She interns as a science writer for Illinois Physics, where she also co-hosts the podcast Emergence along with fellow physics graduate student Mari Cieszynski. When Stover is not doing research or communications, she enjoys hosting her local radio show, singing with her band, and cooking with friends.
Daniel Inafuku graduated from Illinois Physics with a PhD and now works as a science writer. At Illinois, he conducted scientific research in mathematical biology and mathematical physics. In addition to his research interests, Daniel is a science video media creator.
Karmela Padavic-Callaghan, Ph. D. is a science writer and an educator. She teaches college and high school physics and mathematics courses, and her writing has been published in popular science outlets such as WIRED, Scientific American, Physics World, and New Scientist. She earned a Ph. D. in Physics from UIUC in 2019 and currently lives in Brooklyn, NY.
Jamie Hendrickson is a writer and content creator in higher education communications. They earned their M.A. in Russian, East European, and Eurasian Studies from the University of Illinois Urbana-Champaign in 2021. In addition to their communications work, they are a published area studies scholar and Russian-to-English translator.
Garrett R. Williams is an Illinois Physics Ph.D. Candidate and science writer. He has been recognized as the winner of the 2020 APS History of Physics Essay Competition and as a finalist in the 2021 AAAS Science and Human Rights Essay Competition. He was also an invited author in the 2021 #BlackinPhysics Week series published by Physics Today and Physics World.
Karmela Padavic-Callaghan, Ph. D. is a science writer and an educator. She teaches college and high school physics and mathematics courses, and her writing has been published in popular science outlets such as WIRED, Scientific American, Physics World, and New Scientist. She earned a Ph. D. in Physics from UIUC in 2019 and currently lives in Brooklyn, NY.