Asymmetric Wigner molecules in nanowire Y-junctions.

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Materials Science

Background:

• Wigner crystals, crystalline states of interacting electrons, are well-studied in 1D, 2D, and 3D.
• One-dimensional (1D) systems can form two-dimensional (2D) lattices, with the simplest being a three-terminal Y-junction (Y-J).
• Semiconductor Y-junctions, particularly defect-free GaAs/AlGaAs Y-Js, are now experimentally accessible, enabling direct exploration.

Purpose of the Study:

• Investigate the electron gas crystalline state in 2D Y-junctions, contrasting it with 1D systems.
• Explore the two-electron distribution and collective interactions within nanowire Y-Js.
• Analyze the impact of electron density modulation and external electric fields on electron distribution.

Main Methods:

• Utilized a Yukawa-like effective potential to model collective electron interactions.
• Simulated two-electron distributions in nanowire Y-junctions.
• Varied electron density using a screening parameter and applied an external electric field along the Y-axis.

Main Results:

• Observed a transition from quasi-continuous to Wigner molecule-like electron distribution as density decreased.
• Demonstrated that Y-junctions induce equidistant distributions with asymmetric densities, unlike the symmetric 1D Wigner regime.
• Confirmed that external electric fields influence these asymmetric distributions.

Conclusions:

• Nanowire Y-junctions exhibit distinct electron crystalline states compared to strictly 1D systems.
• Electron density and external fields are critical parameters controlling Wigner molecule formation and density asymmetry in Y-junctions.
• These findings pave the way for experimental studies of quantum electron behavior in novel semiconductor geometries.