Superconductivity in a two-dimensional Electron Gas

TL;DR

Recent experiments show that a two-dimensional electron gas can exhibit superconductivity at zero temperature, challenging traditional theories that prohibit metallic states in 2D systems.

Contribution

This paper analyzes experimental data and theoretical principles to propose that the observed conducting phase in 2D electron gases is a zero-temperature superconductor with inhomogeneous charge density.

Findings

Evidence of 2D superconductivity at zero temperature

Inhomogeneous charge density in the superconducting phase

Contradiction of conventional 2D metallic theory

Abstract

In a series of recent experiments, Kravchenko and colleagues observed unexpectedly that a two-dimensional electron gas in zero magnetic field can be a conductor. The two-dimensionality was imposed by confining the electron gas to move laterally at the interface between two semiconductors. The observation of a conductor in two dimensions (2D) is surprising as the conventional theory of metals precludes the presence of a metallic state at zero temperature in 2D. Nonetheless, there are now several experiments confirming the existence of the new conducting phase in a dilute two-dimensional electron gas in zero magnetic field. Here we argue based on an analysis of the experiments and general theoretical grounds that this phase is a zero-temperature superconductor with an inhomogeneous charge density.