A layer of niobium diselenide (NbSe2) just a few atoms thick can conduct electricity with zero resistance.
Most 3D superconducting materials lose this ability once they are in their 2D form. Miguel Ugeda at the nanoGUNE research centre in San Sebastian, Spain, Michael Crommie at the University of California, Berkeley, and their colleagues studied the behaviour of electrons in a single layer of NbSe2, grown on a bilayer of atom-thick carbon.
As the team lowered the temperature to below −271 °C, the material's resistance fell to zero. The authors say that the results confirm that NbSe2 is a true 2D superconductor, a class of materials that could one day be used in tiny quantum computers and other devices.
The team also saw ripples in electron density while the material was superconducting — an effect that some theories predict should not be possible.
Nature Phys. http://doi.org/89 (2015)