Two-dimensional electron liquids: Looking for novel forms of superconductivity
Truly two-dimensional objects are rare. Even a thin piece of paper is trillions of atoms thick. When physicists do succeed in producing 2D systems, quantum interactions can lead to new phenomena and Nobel prizes. Two examples: graphene -- single-atom-thick sheets of carbon atoms -- has unique mechanical, electrical, and optical properties; and two-dimensional electron gases (2DEG) -- planar collections of electrons supported at the interface between certain semiconductors such as gallium arsenide -- allow the observation of such emergent behaviors as the quantum Hall effect and the spin Hall effect. Using an overlying bath of ionic liquid, a piece of superconductor -- divided by an insulating strip -- supports narrow tunnels which permit currents to flow between.