Most superconductors have more than one energy band where electrons can pair up to flow without resistance. But the complex behavior of such multiband superconductivity has been difficult to study experimentally. Electrons scatter off crystal defects and jump between bands, making the material behave as a single-band superconductor through the so-called interband proximity effect. Now Qili Li at the Karlsruhe Institute of Technology in Germany and his colleagues have demonstrated a method for overcoming this hurdle [1]. Their experiments rigorously test current theories of multiband superconductors and lay the groundwork for accessing many predicted quantum effects in these systems.
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