Today, an international team of researchers led by Séamus Davis, Professor of Physics at the University of Oxford and University College Cork, announced results that reveal the atomic mechanism behind high-temperature superconductors. . The findings are published in PNAS.
Superconductors are materials that can conduct electricity with zero resistance, so an electric current can persist indefinitely. These are already used in various applications, including MRI scanners and high-speed maglev trains, but superconductivity typically requires extremely low temperatures, which limits their widespread use. One of the main goals of physics research is to develop superconductors operating at room temperature, which could revolutionize the transport and storage of energy.
Some copper oxide materials exhibit superconductivity at higher temperatures than conventional superconductors, but the underlying mechanism has remained unknown since their discovery in 1987.
To study this, an international team involving scientists from Oxford, Cork in Ireland, the United States, Japan and Germany, has developed two new microscopy techniques. The first of these measured the difference in energy between the orbitals of copper and oxygen atoms, depending on their location. The second method measured the magnitude of the electron pair wave function (the superconductivity force) at each oxygen atom and at each copper atom.
“By visualizing the strength of superconductivity as a function of differences between orbital energies, we were able for the first time to accurately measure the relationship required to validate or invalidate one of the main theories of high-temperature superconductivity, at the atomic scale,” Professor Davis said.
As predicted by theory, the results showed a quantitative inverse relationship between the difference in charge transfer energy between adjacent oxygen and copper atoms and the strength of superconductivity.
According to the research team, this discovery could be a historic step towards the development of room temperature superconductors. Ultimately, these could have far-reaching applications ranging from maglev trains, nuclear fusion reactors, quantum computers, and high-energy particle accelerators, not to mention super-efficient energy transfer and storage. .
In superconducting materials, electrical resistance is minimized because current-carrying electrons are bound together in stable “Cooper pairs”. In low temperature superconductors the Cooper pairs are held together by thermal vibrations, but at higher temperatures they become too unstable. These new results demonstrate that, in high-temperature superconductors, the Cooper pairs are instead held together by magnetic interactions, with the electron pairs bonding via quantum mechanical communication through the intermediate oxygen atom.
Professor Davis added that “this has been one of the holy grail problems in physics research for almost 40 years. Many people believe that cheap and readily available room temperature superconductors would be revolutionary for civilization as well. human than the introduction of electricity itself.”
Atomic-scale window on superconductivity paves the way for new quantum materials
Shane M. O’Mahony et al, on the electron pairing mechanism of high temperature superconductivity of copper oxide, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2207449119
Provided by Oxford University
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