Wigner crystallization in quantum electron bilayers

TL;DR

This paper uses density functional theory to map out the phase diagram of quantum electron bilayers, revealing conditions for liquid and various crystalline phases, including Wigner crystallization, and detailing phase transitions and symmetry changes.

Contribution

It provides the first detailed phase diagram of quantum electron bilayers, identifying multiple crystalline phases and their transition boundaries based on electron density and inter-layer distance.

Findings

Liquid phase at high electron densities

Wigner crystallization into four crystalline phases at lower densities

Phase boundaries include first and second order transitions

Abstract

The phase diagram of quantum electron bilayers in zero magnetic field is obtained using density functional theory. For large electron densities the system is in the liquid phase, while for smaller densities the liquid may freeze (Wigner crystallization) into four different crystalline phases; the lattice symmetry and the critical density depend on the the inter-layer distance. The phase boundaries between different Wigner crystals consist of both first and second order transitions, depending on the phases involved, and join the freezing curve at three different triple points.