From a few to many electrons in quantum dots under strong magnetic fields: Properties of rotating electron molecules with multiple rings

TL;DR

This paper investigates the properties of rotating electron molecules in quantum dots under strong magnetic fields, revealing a non-rigid, mixed phase with crystalline and liquid-like features for systems with 10 to 30 electrons.

Contribution

It introduces a symmetry-breaking and restoration method to analyze multi-ring rotating electron molecules, providing an analytic energy expression applicable to various configurations.

Findings

Finite rotating electron molecules consist of multiple rings rotating independently.

These molecules exhibit non-rigid rotational inertia with crystalline and liquid-like characteristics.

The results contrast with classical rigid Wigner crystal models in high magnetic fields.

Abstract

Using the method of breaking of circular symmetry and of subsequent symmetry restoration via projection techiques, we present calculations for the ground-state energies and excitation spectra of N-electron parabolic quantum dots in strong magnetic fields in the medium-size range 10 <= N <= 30. The physical picture suggested by our calculations is that of finite rotating electron molecules (REMs) comprising multiple rings, with the rings rotating independently of each other. An analytic expression for the energetics of such non-rigid multi-ring REMs is derived; it is applicable to arbitrary sizes given the corresponding equilibrium configuration of classical point charges. We show that the rotating electron molecules have a non-rigid (non-classical) rotational inertia exhibiting simultaneous crystalline correlations and liquid-like (non-rigidity) characteristics. This mixed phase appears in high magnetic fields and contrasts with the picture of a classical rigid Wigner crystal in the lowest Landau level.