Researchers at the U.S. Department of Energy's Brookhaven National Laboratory have combined atoms with multiple orbitals and precisely pinned down their electron distributions.
Using advanced electron diffraction techniques, the scientists discovered that orbital fluctuations in iron-based compounds induce strongly coupled polarizations that can enhance electron pairing-the essential mechanism behind superconductivity.
Brookhaven Lab physicist and project leader Yimei Zhu said that for the first time, they obtained direct experimental evidence of the subtle changes in electron orbitals by comparing an unaltered, non-superconducting material with its doped, superconducting twin.
Brookhaven Lab physicist and study coauthor Weiguo Yin said that now superconductor theory can incorporate proof of strong coupling between iron and arsenic in these dense electron cloud interactions.
He said that this unexpected discovery brings together both orbital fluctuation theory and the 50-year-old 'excitonic' theory for high-temperature superconductivity, opening a new frontier for condensed matter physics.
Yin asserted that high-temperature copper-oxide superconductors, or cuprates, contain in effect a single orbital and lack the degree of freedom to accommodate strong enough interactions between electricity and the lattice.
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He said that the barium iron arsenic we tested has multi-orbital electrons that push and pull the lattice in much more flexible and complex ways, for example by inter-orbital electron redistribution.
Yin said that this feature is especially promising because electricity can shift arsenic's electron cloud much more easily than oxygen's.
The study has been published in the journal Physical Review Letters.